Ultracytochemical localization of Ca++-ATPase activity in the paraphyseal epithelial cells of the frog, Rana esculenta

Effects of 10 T static magnetic field on the function of sperms and their offspring in Caenorhabditis elegans

With the wide application of static magnetic fields (SMFs), the risk of living organisms exposed to man-made magnetic fields that the intensity is much higher than geomagnetic field has gradually increased. Reproductive system is highly sensitive to environmental stress; however, the influence of high SMFs on reproduction system is still largely unknown. Here we explored the biological responses of SMFs exposure at an intensity of 10 T on the sperms and their offspring in him-5 male mutants of Caenorhabditis elegans (C. elegans). The size of unactivated sperms was deceased by 10 T SMF exposure, instead of the morphology. Exposure to 10 T SMF significantly altered the function of sperms in him-5 worms including the activation of sperms and the non-transferred ratio of sperms. In addition, the brood size assay revealed that 10 T SMF exposure eventually diminished the reproductive capacity of him-5 male worms. The lifespan of outcrossed offspring from exposed him-5 male mutants and unexposed fog-2 female mutants was decreased by 10 T SMF in a time dependent manner. Together, our findings provide novel information regarding the adverse effects of high SMFs on the sperms of C. elegans and their offspring, which can improve our understanding of the fundamental aspects of high SMFs on biological system.

Histological reinterpretation of paraphysis cerebri in Ambystoma mexicanum

Intraventricular and extraventricular choroid plexuses are neuroepithelial folds which arise from the roof of the diencephalon. We describe the circumventricular structure of the diencephalon roof (paraphysis cerebri) during the various development stages of Ambystoma mexicanum. The parasagittal sections of the larvae epithalamus exhibit the presence, in addition to the epiphysis, of two dorsal primordia in nearby areas, which appear to be extraventricular saccular evaginations of different origin that give rise to two structures we define as the anterior extraventricular choroid plexus (AEP) and posterior extraventricular choroid plexus (PEP). During larvae development, the primordia arise perpendicular to each other, grow and show luminal folds and invaginations. Later, the two extraventricular evaginations, which are separate units, become interrelated. As the PEP grows, it covers the AEP dorsally, but it is difficult to define the borders of these organs. AEP is formed by alveolar-acinar epithelial aggregates with evidence of secretion-like content. PEP structure is like a choroid plexus, but its position is extraventricular and dorsal to the AEP. The PEP is always between the AEP and the meninges and can be small or large in size. This means that in A. mexicanum, the paraphysis cerebri is made up of two adjacent organs, which arise almost simultaneously from two different primordia (the AEP and the PEP) and as the posterior one grows, it overlaps the anterior one and masks itself. In conclusion, we suggest that AEP and PEP are homologous to paraphysis cerebri and the dorsal sac, respectively.

Roles of arginine vasotocin receptors in the brain and pituitary of submammalian vertebrates

This chapter reviews the functions of arginine vasotocin (AVT) and its receptors in the central nervous system (CNS) of primarily submammalian vertebrates. The V1a-type receptor, which is widely distributed in the CNS of birds, amphibians, and fish, is one of the most important receptors involved in the expression of social and reproductive behaviors. In mammals, the V1b receptor of arginine vasopressin, an AVT ortholog, is assumed to be involved in aggression, social memory, and stress responses. The distribution of the V1b-type receptor in the brain of submammalian vertebrates has only been reported in an amphibian species, and its putative functions are discussed in this review. The functions of V2-type receptor in the CNS are still unclear. Recent phylogenetical and pharmacological analyses have revealed that the avian VT1 receptor can be categorized as a V2b-type receptor. The distribution of this newly categorized VT1 receptor in the brain of avian species should contribute to our knowledge of the possible roles of the V2b-type receptor in the CNS of other nonmammalian vertebrates. The functions of AVT in the amphibian and avian pituitaries are also discussed, focusing on the V1b- and V1a-type receptors.

Static magnetic field accelerates aging and development in nematode

Electro-magnetic fields are everywhere in our life. The strength and duration of human exposure is proportional to the degree of industrialization. The possible health hazard has been investigated for decades. C. elegans (nematode) has been a sensitive tool to study aging and development. The current study investigated the possible effects of static magnetic fields (SMFs) on the developmental and aging processes of C. elegans. Nematodes were grown in the presence of SMFs of strengths varying from 0 to 200 mT. Treatment with a 200 mT SMF reduced the development times from L2 to young adult by approximately 20%. After SMF treatment, the average lifespan was reduced from 31 days to 25 days for wild-type nematodes. The upregulation of genes associated with development and aging was verified by quantitative real-time RT-PCR. Nematodes carrying mutation in these genes also exhibited resistance to the SMFs treatment. Apparently, induction of gene expression is selective and dose-dependent. SMFs accelerate nematode development and shorten nematode lifespan through pathways associated with let-7, clk-1, unc-3 and age-1.

Effects of static magnetic fields on the development and aging of Caenorhabditis elegans

The current study investigated the possible effects of static magnetic fields (SMFs) on the developmental and aging processes of Caenorhabditis elegans. Nematodes were grown in the presence of SMFs of strengths varying from 0 to 200 mT. The rate of development and the lifespan were recorded. Treatment with a 200 mT SMF reduced the development time from the L2 to the L3 stage by 20%, from L3 to L4 by 23%, and from L4 to young adult by 31%. After SMF treatment, the average lifespan was reduced from 31 days to 24 days for wild-type nematodes. The up-regulation of clk-1, lim-7, daf-2, unc-3 and age-1 after SMF treatment was verified by quantitative real-time RT-PCR. Apparently, induction of gene expression is selective and dose dependent. The total developmental time was significantly reduced for the lin-4, lin-14, lin-41 and lim-7 mutants, but not for the let-7, clk-1, unc-3 and age-1 mutants. Lifespan analyses revealed that the let-7, unc-3 and age-1 mutants were not affected by SMF treatment. Here we show that SMFs accelerate nematode development and shorten nematode lifespan through pathways associated with let-7, clk-1, unc-3 and age-1.

Calcium-dependent ATPase unlike ecto-ATPase is located primarily on the luminal surface of brain endothelial cells

Numerous cytochemical studies have reported that calcium-activated adenosine triphosphatase (Ca2+-ATPase) is localized on the abluminal plasma membrane of mature brain endothelial cells. Since the effects of fixation and co-localization of ecto-ATPase have never been properly addressed, we investigated the influence of these parameters on Ca2+-ATPase localization in rat cerebral microvessel endothelium. Formaldehyde at 2% resulted in only abluminal staining while both luminal and abluminal surfaces were equally stained following 4% formaldehyde. Fixation with 2% formaldehyde plus 0.25% glutaraldehyde revealed more abluminal staining than luminal while 2% formaldehyde plus 0.5% glutaraldehyde produced vessels with staining similar to 4% and 2% formaldehyde plus 0.25% glutaraldehyde. The abluminal reaction appeared unaltered when ATP was replaced by GTP, CTP, UTP, ADP or when Ca2+ was replaced by Mg2+ or Mn2+ or p-chloromercuribenzoate included as inhibitor. But the luminal reaction was diminished. Contrary to previous reports, our results showed that Ca2+-specific ATPase is located more on the luminal surface while the abluminal reaction is primarily due to ecto-ATPase. The strong Ca2+-specific-ATPase luminal localization explains the stable Ca2+ gradient between blood and brain, and is not necessarily indicative of immature or pathological vessels as interpreted in the past.

Changes in Ca(++)-ATPase activity in smooth-muscle cell membranes of the canine basilar artery with experimental subarachnoid hemorrhage

Changes in Ca(++)-adenosine triphosphatase (ATPase) activity in the plasma membrane of smooth-muscle cells in the basilar arteries of dogs with experimental subarachnoid hemorrhage (SAH) were examined. The study methods included electron microscopic histochemistry and bioassay of the enzyme that exports cytoplasmic Ca++ to extracellular spaces. The Ca(++)-ATPase activity in the basilar artery increased significantly in response to the application of vasoconstrictive agents (prostaglandin F2 alpha and a phorbol ester), but decreased significantly 24 hours after experimental SAH, inversely with basilar artery contraction. Dogs that had undergone two arterial blood injections (double SAH) exhibited a further decrease in Ca(++)-ATPase activity as well as persistent contraction of the basilar artery for a longer period (at least 7 days) than was seen in animals with a single arterial blood injection. Bioassay of the enzyme also demonstrated a decrease in vascular Ca(++)-ATPase activity in dogs subjected to double SAH. These findings suggest that the early occurrence of and long-lasting decrease in Ca(++)-ATPase activity in dogs with experimental SAH induces a persistent disturbance of Ca++ homeostasis and indicates that damage to the plasma membrane in the cerebral arterial smooth-muscle cells proceeds to myonecrosis after SAH.

Ultrastructure of the paraphysis in Bufo bufo larvae

A study of the ultrastructure and function of the paraphysis in Bufo bufo larvae was carried out. The structure is a tubular-ramified gland made up of numerous tubules with monolayered epithelial walls surrounded by connective tissue and sinusoids. The epithelial cells secrete glycoprotein to contribute to production of the cephalorachidian fluid. The role of the paraphysis in the transport of fluids and electrolytes from the blood to the cephalorachidian fluid in regulation of ionic and osmotic homeostasis is discussed.

Ultrastructural localization of Ca2(+)-binding sites in the middle ear mucosa of the rat

Cations were precipitated with potassium-pyroantimonate in the middle ear mucosa of the rat and the distribution of the formed precipitates was studied by electron microscopy. The precipitate density in various cells of the different epithelia of the middle ear mucosa was determined on electron micrographs by counting the number of precipitates per unit area. Electron spectroscopic imaging was also performed to obtain information about the spatial distribution of the precipitates and their elemental composition.

Ultracytochemical localization of Ca2(+)-ATPase activity in the middle ear mucosa of the guinea pig

Ca2(+)-ATPase activity was studied ultra-cytochemically in the middle ear mucosa of the guinea pig. On electron microscopic examination, the most intense reaction was found on the microvilli. Reaction products were also observed on the cilia and around and between the secretory granules on the apical side of the cells in their secretory phase. The basolateral membranes contained few reaction products, while very little or no activity was found on the basal membrane.

Ultracytochemical study of capillary Ca2+-ATPase activity in brain edema

To investigate the functional relationship between astrocytes and Ca2+-ATPase of cerebral capillary endothelial cells (capillary Ca2+-ATPase), cold lesions were produced and the cytochemical reaction (CR) for Ca2+-ATPase activity and morphological changes of astrocytes were chronologically studied. Under normal conditions, CR for capillary Ca2+-ATPase activity was mild. However, at 20 min after the operation, astrocytic end-feet embracing the capillaries were swollen, and CR was moderate. Deposits of slightly coarsened reaction product (RP) appeared and accumulated on the abluminal surface. CR became stronger as edema fluid accumulated. At 4, 7 and 15 days, detachment of the astrocytic processes from the capillary wall was observed and in the uncovered capillaries, CR was intense, especially on the abluminal surface. It could be thus possible that the enzyme was related to the blood-brain barrier (BBB). At 2 months, reactive astrocytes had recovered lesion-resistant capillaries. CR was mild and its associated deposits were coarser, the number decreasing on both surfaces. The nature and localization of the deposits of RP in the scar were different from those under normal conditions, possibly due to the functional differences between normal and reactive astrocytes in the BBB. CR was mild in association with astrocytes embracing the capillary wall and was intense without astrocytes. Therefore, it might be possible that astrocytes exerted certain effects on capillary Ca2+-ATPase activity in relation to BBB function.

Cytochemical localization of Ca2+-ATPase activity in peripheral nerve

We used an electron microscopic cytochemical method to determine the localization of Ca2+-ATPase in rat peripheral nerve. We found that reaction product occurred along most cytoplasmic membranes in the dorsal root ganglia (DRG). Unmyelinated axons demonstrated reaction product on the axolemma diffusely along their length. Myelinated fibers, in contrast, had reaction product limited to the axolemma in the paranodal region. Internodal axolemma never showed reaction product and nodal axolemma was only occasionally stained, usually in sections reacted for the maximum times. Schwann cell plasma membranes uniformly showed reaction product. The restricted localization of Ca2+-ATPase to the paranodal region of myelinated fibers suggests that calcium efflux may occur principally at those sites.

Ultracytochemical investigation of calcium-activated adenosine triphosphatase (Ca++-ATPase) in chick tibia

The ultrastructural distribution of Ca++-ATPase in bone cells of growing chick tibia was investigated by a cytochemical method in order to gain insight into possible sites of calcium ion translocation. Both osteoclasts and osteoblasts showed a polar distribution of reaction product along the plasma membrane. In osteoclasts, enzymatic activity occurred along the portion of the plasma membrane facing the marrow but not along the ruffled border or clear zone. The reaction product in these cells was due solely to Ca++-ATPase action. In osteoblasts, the plasma membrane facing away from bone (apical and lateral membrane) was very intensely stained, whereas the basal membrane was unstained. The reaction product in these cells appeared to be the result of both Ca++-ATPase and Ca++,Mg++-ATPase. In osteocytes, no plasma membrane staining was detectable. Mitochondrial staining in all three types of cells was more sensitive to fixation than was the plasma membrane enzyme, suggesting that mitochondrial and plasma membrane Ca++-ATPases are chemically distinct, as biochemical studies have shown. In general, mitochondria in osteoclasts stained more intensely than those in osteoblasts or osteocytes. Mitochondrial and vesicular sites of activity may be related to intracellular calcium storage, whereas calcium ATPases of the plasma membrane are presumed to be involved in calcium efflux from the cells. Calcitonin treatment did not alter the enzymatic distribution or intensity in osteoclasts. The striking polar distribution of both osteoclast and osteoblast plasma-membrane activity suggests that directional calcium pumping by these cells may be of importance in bone-forming and bone-resorbing mechanisms.

Electron microscopic cytochemical localization of a basolateral calcium adenosine triphosphatase in vitamin D replete chick enterocytes

A cytochemical technique for the electron microscopic localization of calcium adenosine triphosphatase (Ca-ATPase) was utilized to localize this enzyme in the enterocytes of rachitic and vitamin D-replete chicks. In animals treated with cholecalciferol (CC, vitamin D3), an electron-dense reaction product was located along the basolateral membranes of the absorptive cells within 72 hr after injection. Similarly, a reaction product was identified in association with the basolateral membranes within 24 hr after injection of 1,25-dihydroxycholecalciferol, the active metabolite of vitamin D. A microvillar reaction product was not seen in either of these two groups. Electron-dense reaction products were also seen in association with mitochondria and scattered throughout the cytoplasm of these enterocytes. The Ca-ATPase reaction product was dependent upon the presence of medium calcium and substrate (ATP), was inhibited by vanadate, and was heat labile. In the rachitic animals, a reaction product indicative of Ca-ATPase activity was not seen in association with either the basolateral membranes or the mitochondria. These data appear to indicate that an energy-requiring calcium-activated membrane pump plays a role in the flux of calcium across the enterocytes of the small intestine.

Cytochemical localization of Ca++-ATPase activity in the lateral cochlear wall of the guinea pig

Ca++-ATPase activity was examined cytochemically in the lateral cochlear wall of the guinea pig. The reaction products showing Ca++-ATPase activity were found along the folded plasma membrane of the strial marginal cells. In contrast, little or no reaction was seen on the apical surfaces of these cells. There were also marked reaction products on the microvilli and the endolymphatic cell surface of Reissner's membrane, and the apical and lateral plasma membranes of the spiral prominence and the external sulcus cells. These reactions completely disappeared when Ca++ or ATP was removed from the incubation medium. Our results strongly suggest that Ca++-ATPase plays an important role in Ca++ transport system for the regulation of Ca++ concentration in the cochlear endolymph.

Cytochemical studies of Ca++-ATPase activity in the vestibular epithelia of the guinea pig

We used ultracytochemistry to examine Ca++-ATPase activity in the vestibular epithelia of the guinea pig. Many reaction products were found along the basolateral plasma membrane of the vestibular dark cell. There were also marked reaction deposits on the apical and lateral cell membranes of the transitional cells, and the utricular and saccular wall cells. Both sensory and supporting cells showed Ca++-ATPase activity along their ciliary membrane and apical-lateral cell surfaces. Our findings indicate that the Ca++-ATPase activity found on the plasma membrane is closely related to Ca++-transport across the plasma membrane. When either Ca++ or ATP was omitted from the incubation medium, enzyme activity (as seen by the staining reaction present) was completely abolished. Our present results suggest that Ca++-ATPase located in the vestibular epithelia plays a significant role in the regulation of the Ca++-concentration in the vestibular endolymph.

Histochemical localization of adenosine triphosphatase activity in thymus: a light microscopical and ultrastructural study

Ultrastructural localization of ATPase at high pH in the presence of Ca2+ showed that activity in thymocyte precursors was stronger than in mature thymocytes. The activity was localized in the nuclear envelope, rough endoplasmic reticulum, Golgi apparatus and mitochondria. The difference in activity was attributed to a marked decrease in ATPase-containing organelles, mainly the endoplasmic reticulum in the mature thymocytes. This appears to be related to the proliferative activity of the cells rather than to the immunological maturity of the thymocytes. A very strong activity, also localized in the same organelles, was present in the macrophages and interdigitating cells which might have a secretory function and possibly contribute to thymocyte maturation. The Ca2+-ATPase activity in the nuclear envelope-endoplasmic reticulum system suggests that these may be the sites for storage and regulation of cytoplasmic calcium.

Ultrahistochemical localization of Na+-K+ ATPase, Ca2+-ATPase and alkaline phosphatase activity in a calcium-transporting epithelium of a crustacean during moulting

Periodical changes in Na+-K+-ATPase, Ca2+-ATPase and non-specific alkaline-phosphatase activity were observed using cytochemical techniques in the posterior caeca of the crustacean amphipod, Orchestia cavimana, during the moult cycle. These changes were considered in relation to the calcium transport mechanisms in the posterior caecal epithelium. For both ATPases as well as alkaline phosphatase, the specific reaction products were most intense during the pre-exuvial period, i.e. when calcium is slowly transported against a concentration gradient: the localization of Na+-K+-ATPase activity in microvilli and the upper extracellular channels strongly supports the hypothesis that this enzyme is involved in an indirect, sodium-dependent mechanism for the transport of calcium. The detection of Ca2+-ATPase activity in microvilli would seem to indicate that this enzyme plays a role in the direct, active extrusion of Ca2+ at this level. Although the role of alkaline phosphatase in the transport of calcium remains unclear, the histochemical detection of this enzymatic activity throughout the apical part of the caecal epithelium suggests that this enzyme may be involved in calcium secretion. In post-exuvial period, we found only weak specific reaction products, thus indicating a reduced active calcium transport as these ions are rapidly reabsorbed down the concentration gradient.

Histochemical and cytochemical demonstration of Ca++-ATPase activity in the stellate cells of the adenohypophysis of the guinea pig

The histo- and cytochemical localization of Ca++-ATPase activity in the adenohypophysis of the guinea pig was studied utilizing a newly developed method (Ando et al. 1981). An intense reaction was observed in the wall of the blood vessels and between non-secretory cells (stellate cells) and endocrine cells of the pars distalis. Under the electron microscope the Ca++-ATPase reaction product was located extracellularly in relation to the plasmalemma of the stellate cells. This reaction was dependent on Ca++ and the substrate, ATP, and reduced by the addition of 0,1 mM quercetin to the standard incubation medium. Preheating of the sections before incubation completely inhibited the enzyme activity. When Mg++ in different concentrations were substituted for Ca++ in the incubation medium the reaction was always reduced. Both Ca++ and Mg++ in the incubation medium also reduced the reaction. The plasmalemma of the endocrine cells contains no demonstrable amount of Ca++-ATPase activity. The function of the Ca++-ATPase activity is discussed in relation to the regulation of the extracellular Ca++ concentration which seems to be important with respect not only to the secretory process of the endocrine cells but also to the metabolism of the adenohypophysis.

Occurrence of bone fractures and parathyroid hyperplasia in paraphysectomized frogs (Rana catesbeiana)

The physiological role of the amphibian paraphysis was studied by removing the paraphysis from bullfrog tadpoles (Rana catesbeiana) and observing change in frog weight, bone development, and parathyroid glands 22 months later. Development was similar in control and paraphysectomized frogs until 6 months when the experimental frogs began to show greater weight gain which persisted for the remaining 16 months. At the time of sacrifice (22 months after paraphysectomy), the parathyroid glands of the experimental frogs were enlarged with a tenfold increase in wet weight and a sevenfold increase in dry weight. The glands from experimental frogs had numerous cysts filled with eosinophilic staining material; histologically the cell nuclei were rounded and the cytoplasm was vesiculated. At the time of sacrifice the experimental frogs had knoblike deformities along the shafts of the long bones. These deformities were due to callus formation around spontaneous bone fractures as revealed by X-rays of the tibia-fibulas and femurs. The dry weight was greater but calcium content less in femurs from experimental frogs. These findings indicate the paraphysis plays a role in calcium metabolism, possibly by producing a factor necessary for calcium action on cells.

Ultracytochemical study of Ca++-ATPase and K+-NPPase activities in retinal photoreceptors of the guinea pig

Ca++-ATPase activity was demonstrated histochemically at light- and electron-microscopic levels in inner and outer segments of retinal photoreceptor cells of the guinea pig with the use of a newly developed one-step lead-citrate method (Ando et al. 1981). The localization of ouabain-sensitive, K+-dependent p-nitrophenylphosphatase (K+-NPPase) activity, which represents the second dephosphorylative step of the Na+-K+-ATPase system, was studied by use of the one-step method newly adapted for ultracytochemistry (Mayahara et al. 1980). In retinal photoreceptor cells fixed for 15 min in 2% paraformaldehyde the electron-dense Ca++-ATPase reaction product accumulated significantly on the inner membranes of the mitochondria but not on the plasmalemma or other cytoplasmic elements of the inner segments. The membranes of the outer segments remained unstained except the membrane arrays in close apposition to the retinal pigment epithelium. The cytochemical reaction was Ca++- and substrate-dependent and showed sensitivity to oligomycin. When Mg++-ions were used instead of Ca++-ions, a distinct reaction was also found on mitochondrial inner membranes. In contrast to the localization of the Ca++-ATPase activity, the K+-NPPase activity was demonstrated only on the plasmalemma of the inner segments, but not on the mitochondria, other cytoplasmic elements or the outer segment membranes. This reaction was almost completely abolished by ouabain or by elimination of K+ from the incubation medium.