Differential activation of mitogen-activated protein kinases by methyl methanesulfonate in the kidney of young and old rats

Mitogen-activated protein kinases (MAPKs) play a critical role in the regulation of cell proliferation, differentiation and apoptosis. We evaluated MAPKs, extracellular signal-regulated kinases (ERKs), c-Jun NH2-terminal kinases (JNKs) and p38 MAPKs in the kidney of young and old rats in response to a direct-acting alkylating agent, methyl methanesulfonate (MMS). It is shown that the basal activity of ERKs was strongly down-regulated in the kidney of old rats compared to their young counterparts without a significant difference in the basal expression of ERKs. Upon treatment with MMS, ERKs were deactivated about 5-fold (P<0.05) in the kidney of young rats, whereas they were activated about 4-fold (P<0.01) in old rats. Strikingly, expression of JNKs was not detected in old animals, whereas it was clearly present and strongly activated after MMS treatment in the kidney of young animals. The basal activity of p38 significantly increased in the kidney of old rats as compared to young animals, whereas no difference in the basal expression of p38 was detected. After treatment with MMS, p38 was activated in the kidney of both young and old rats, where activation was dramatically stronger than in young animals. Taken together, these results demonstrate age-specific MAPKs signaling pathways in the rat kidney. The implications in age-related changes in susceptibility of the kidney to MMS-induced carcinogenesis are discussed.     

Globular protein hydration by a differential dielectrometric method]

A differential method is described for measuring dielectric constants and losses in aqueous protein solutions at millimetrerange wavelengths. Employment of the method allows to improve the accuracy of determining the degree of hydratation. A method has also been suggested for taking into account the contribution of ions to the dielectric constant of solutions. The differential method was used to study hydratation of nine globular proteins. The data obtained are compared with the corresponding values provided by other experimental techniques and with theoretical predictions based on some models of hydratation. Good agreement is obtained with results provided by the isopiestic and NMR techniques. The discrepancy shown for hemoglobin is discussed in the paper. As has been shown, the dielectric method registers a monomolecular surface layer of water only. With pH varying between 4.0 and 3.2, a significant increase is observed in the hydratation of serum albumin. Presumably, this effect is connected with a N--F conformational transition.     

Pollen of the Butomaceae and Alismataceae

When the microspores of B. umbellatus are released from the tetrad the developing wall consists only of muri and pilae (bacula). A basal layer is subsequently formed on unitmembrane-like strands. The latter appear to be formed de novo in association with the microspore cell membrane. As a basal layer develops an outer consolidated and an inner stranded layer are differentiated. These are considered ontogenetically equivalent and no terminological distinction appears justified. The basal layer and sexine are not differentiated by basic fuchsin or electron stains. Thus, the stranded (or nonhomogeneous) and amorphous-granular (or homogeneous) types of exine fine structure are histochemically indistinguishable in this species. Concomitant cytoplasmic activity, particularly in the peripheral region of the cell, may be related to substrate or enzyme synthesis, transport, and deposition. Several “unusual” vesicle types are tentatively related to other phases of morphogenetic activity in the protoplast.     

Histology and Ultrastructure of the Body Wall in the Phoronid Phoronopsis harmeri

The histology and ultrastructure of the body wall in Phoronopsis harmeriwere studied using light microscopy and TEM. The ectoderm epithelium of tentacles, anterior body region, and ampulla consists of monociliary cells. Gram-negative bacteria were found between microvilli, in the protocuticle of the anterior region, and in the ampulla. The epithelium of the posterior body region lacks both monociliary cells and bacteria. The bundles of nerve fibers run between the layer of epithelial cells and basal membrane. The musculature of the body wall comprises circular and longitudinal muscles. The circular muscle fibers are applied to the basal membrane and constitute a solid layer extending almost throughout the length of the body. This pattern is broken in the posterior body region, where there is no solid layer of circular musculature, and the latter is arranged in isolated muscle bands. In the ampullar (terminal) body region, the inversion of circular and longitudinal muscle layers takes place, so that the latter appears to be pressed against the basal membrane. The apical surfaces of longitudinal muscle cells bear cytoplasmic processes; some of the cells have a flagellum. The basal portion of the longitudinal muscle cells forms a cytoplasmic process containing bundles of tonofilaments. The processes of all cells making up the muscle bands are interwoven and anchored to the basal membrane.     

The ultrastructure of the salt gland of Spartina foliosa

Summary The salt gland in Spartina foliosa is composed of two cells, a large basal cell and a smaller, dome-shaped cap cell which is located on a neck-like protrusion of the basal cell. There is no cuticular layer separating the salt gland from the mesophyll tissue. The basal cell has dense cytoplasm which contains numerous mitochondria, rod-like wall protuberances, and infoldings of the plasmalemma which extend into the basal cell and partition the basal cell cytoplasm. The protuberances originate on the wall between the basal and the cap cells and are isolated from the basal-cell cytoplasm by the infoldings of the plasmalemma. While the cap cell has no partitioning membrane system or wall protuberances, it resembles the basal cell by having dense cytoplasm and numerous mitochondria.The basal cell seems to be designed for efficient movement of ions toward the cap cell. The long, dead-end extracellular channels in the basal cell of Spartina appear comparable to surface specializations seen in the secreting epithelium of animal cells which carry out solute-linked water transport. The number of mitochondria and their close association with the plasmalemma extensions suggest that they have an important role in the transfer of ions through the basal cell.The accumulated ions would move into the extracellular spaces along an osomotic gradient where the accompanying passive flow of water would move the ions into the cap-cell wall and from there the solution would pass out through the pores in the cuticle.     

Ultrastructure of the Circulatory System of the Phoronid Phoronopsis harmeri Pixell, 1912. 2. Main vessels

The ultrastructure of the wall of the main blood vessels of the phoronid Phoronopsis harmeri is described. The walls of the lophophoral and left lateral vessels consist of myoepithelial cells of the coelomic lining (peritoneal cells), a thin basal lamina, and an incomplete endothelial lining. In the head region of the body, the wall of the medial vessel consists of myoepithelial cells of the coelomic lining (peritoneal cells), a basal lamina, and true muscular endothelial cells. The anterior part of the medial vessel functions as the heart. In the anterior part of the body, the medial vessel wall consists of five layers: the external nonmuscular coelothelium, a layer of the extracellular matrix, the internal muscular coelothelium, an internal layer of the extracellular matrix, and an incomplete endothelial lining. The complicated structure of the medial vessel wall may be explained by the superimposition of the lateral mesentery on the ordinary vessel wall.     

Embryogenesis in <Emphasis Type="Italic">Sedum acre</Emphasis> L.: structural and immunocytochemical aspects of suspensor development

The changes in the formation of both the actin and the microtubular cytoskeleton during the differentiation of the embryo-suspensor in Sedum acre were studied in comparison with the development of the embryo-proper. The presence and distribution of the cytoskeletal elements were examined ultrastructurally and with the light microscope using immunolabelling and rhodamine-phalloidin staining. At the globular stage of embryo development extensive array of actin filaments is present in the cytoplasm of basal cell, the microfilament bundles generally run parallel to the long axis of basal cell and pass in close to the nucleus. Microtubules form irregular bundles in the cytoplasm of the basal cell. A strongly fluorescent densely packed microtubules are present in the cytoplasmic layer adjacent to the wall separating the basal cell from the first layer of the chalazal suspensor cells. At the heart-stage of embryo development, in the basal cell, extremely dense arrays of actin materials are located near the micropylar and chalazal end of the cell. At this stage of basal cell formation, numerous actin filaments congregate around the nucleus. In the fully differentiated basal cell and micropylar haustorium, the tubulin cytoskeleton forms a dense prominent network composed of numerous cross-linked filaments. In the distal region of the basal cell, a distinct microtubular cytoskeleton with numerous microtubules is observed in the cytoplasmic layer adjacent to the wall, separating the basal cell from the first layer of the chalazal suspensor cells. The role of cytoskeleton during the development of the suspensor in S. acre is discussed.     

Development of the Ciliary Pattern of the Oral Apparatus of Tetrahymena thermophila1

ABSTRACT. The sequence of formation and ciliation of basal bodies and the subsequent organization of compound ciliary structures of the oral apparatus of Tetrahymena thermophila was reanalyzed with the aid of scanning electron microscopy of cells in which the epiplasmic layer was exposed, as well as by light microscopy of protargol-impregnated specimens. This combination of methods allowed the delineation of numerous steps in the patterning of the oral ciliature, some of which have received little or no previous attention. Highlights include: the initial formation of “strings” of nonciliated new basal bodies in juxtaposition to relatively few basal bodies of the stomatogenic kinety; generation of basal body pairs, roughly oriented along the anteroposterior axis of the cell, that later align side-by-side to assemble promembranelles; condensation and reorientation of promembranelles simultaneous with addition of a third row of basal bodies anterior to the original two rows; production of a very short fourth row of basal bodies at the anterior right end of each developing membranelle; generation of the outer basal body row of the undulating membrane (UM) after alignment of the inner row, with transient ciliation of the inner row preceding permanent ciliation of the outer row; limited basal body resorption at the ends of membranelles; and sculpturing of the right ends of membranelles by a movement of basal bodies associated with formation of the ribbed wall adjacent to the UM. In the old anterior oral apparatus a repetition of the processes of generation of a new outer UM row and sculpturing of right ends of membranelles takes place in synchrony with the corresponding events in the oral primordium, following prior shedding of the old outer UM row and loss of the sculptured pattern in association with temporary regression of the ribbed wall micro-tubules. Oral development is complex, with different processes involved in the assembly of the membranelles and the UM, and with a sequence of distinct events involved in the generation of each of these structures. Speaking comparatively, membranelle development follows the same pathway in many, perhaps all, ciliates in which these structures or their homologues develop from a common stomatogenic field.     

Ultrastructure of the Wall of the Germinating Sporangiospore of Linderina pennispora (Mucorales)

Carbon replicas of germinating sporangiospores of Linderinapennispora show the outer wall complex to break open basally,during the phase of swelling, and the surface of the germ tubeto be smooth. Chemical treatment reveal the microfibrillar wallof the germ tube to be continuous with the microfibrillar innerwall complex of the spore. Microfibrils of the germ tube arerandornly arranged and appear to be finer than those of thespore wall. Ultra-thin sections reveal the wall of the germtube to consist of an outer electron-dense layer and an innermicrofibrillar electron-transparent layer and both layers originatein the basal region of the spore between the plasmalemma andthe inner wall complex of the spore.     

Zero order kinetics of cell wall turnover inStaphylococcus aureus

Cells exponentially grown from four strains ofS. aureus (SG 511, H, 52A5G, and248 PN-1) and uniformly labeled in their walls with³H-N-acetylglucosamine, were found to turn over their old walls at constant rates of up to 25% per generation. Wall turnover was not observed to follow first order kinetics, thus ruling out the implication that maintenance of normal wall thickness was achieved by a random distribution of new wall components in the old wall. Instead, wall turnover in all cases strictly followed zero order kinetics, indicating that newly synthesized wall material was placed layer by layer beneath the inner surface of the old cell wall. This finding correlates with evidence obtained from earlier electron microscopic investigations into the regeneration of the staphylococcal cell wall after chloramphenicol treatment. Based on the experimental data presented, a simplified model for wall turnover of the growing staphylococcal cell was proposed. The model also takes into account the finding, derived from additional experiments with strainSG 511, that the total cell wall turned over at a somewhat higher rate than the old portions of the wall. The rates of cell wall turnover found inS. aureus SG 511 are the highest reported to date for pathogenic bacteria. The medical implications of this finding were discussed.     

An electron microscopic study of the closure of the optic fissure in the golden hamster.

During early development of the mammalian eye, invagination and differential growth result in the formation of a cleft, the optic fissure, through which the hyaloid artery reaches the interior of the optic cup. Closure of this fissure was studied by electron microscopy in hamster embryos from days 10 through 12 of gestation. Closure occurred only when and where the basal lamina, which invests the entire wall of the optic cup, had disappeared. No morphological evidence was found that indicated a mechanism for the breakdown of the basal lamina lining the fissure, the fusion of surface cells of opposing sides and restoration of the basal lamina along inner and outer margins of the wall after closure. While in previous light microscopic investigations of the developing human eye eversion of the inner layer into the fissure has been reported, an inversion of the outer layer was found in this study. During inversion cells of the outer layer temporarily changed their orientation. While most of these cells remained within the layer when it returned to its normal position, some cells became separated and degenerated. Inversion of the outer layer, breakdown of the basal lamina and degeneration of superfluous cells appear to be necessary events for a normal closure to occur.     

Unusual electron-dense dome associates with compound plasmodesmata in the embryo-suspensor of genus Sedum (Crassulaceae)

Plasmodesmata ensure the continuity of cytoplasm between plant cells and play an important part in the intercellular communication and signal transduction. During the development of the suspensor of both Sedum acre L. and Sedum hispanicum L., changes in the ultrastructure of plasmodesmata and adjoining cytoplasm are observed. Numerous simple plasmodesmata are present in the inner wall of the two-celled embryo separating the basal cell from the apical cell. From the early-globular to the torpedo stage of embryo development, the part of the wall separating the basal cell from the first layer of the chalazal suspensor cells is perforated by unusual, compound plasmodesmata. The role and the sort of transport through these plasmodesmata are discussed.     

The effects of reserpine and haloperidol on tyrosine hydroxylase activity in the brains of aged rats

Many neurotransmitter systems appear to be altered with aging. The effects of aging on the regulation of tyrosine hydroxylase, the rate-limiting enzyme in the synthesis of catecholamines in the brain has been examined. The endogenous basal activity of tyrosine hydroxylase was lower in the hypothalamus of 24 month old Fisher 344 rats than in the hypothalamus of 3 month old or 6 month old animals. There was no difference in the basal activity of tyrosine hydroxylase in the locus ceruleus, frontal cortex, hippocampus, substantia nigra, or the striatum of rats of ages 3 months, 6 months and 24 months. Tyrosine hydroxylase activity was increased in the striatum of 3 month old (60%) and 6 month old (28%) rats after treatment with haloperidol or reserpine, whereas no change in enzyme activity followed administration of these drugs to 24 month old animals. In conclusion, increases in tyrosine hydroxylase activity in the brain that normally occur in the striatum of 3 month old rats after haloperidol or reserpine treatment are significantly decreased in 6 month old rats and not apparent in 24 month old rats.     

Hypothesis on the mechanism of cnidocyst discharge (author's transl)

The geometic aspects of the cnidocystic filament before invagination, during invagination and after the process of evagination are shown. Experiments are described that allow an approach to study the mechanism of discharge. It is suggested here that the filament is an elastic tube which, when it is intracapsular, is folded and spiraled and thus, under a constraining action. Evagination then consists simply in the release of the constraining force and reversion of the filament to the primitive cylindric shape. The presence of water seems indispensable to the process to take place; however this does not necessarily imply that a hydratation take place in the filament wall. It also seems obvious that if expansion is a normal tendency of the constrained filament, eversion is a result of the continuity between the wall of the filament and that of the capsule. In conclusion, the invagination of the tube during cnidogenesis may be interpreted as a mean of storing energy for the evagination.     

Serial Development of Foliar Gemmae in Tortula (Pottiales, Musci), an Ultrastructural Study

The development and liberation mechanism of foliar gemmae havebeen studied by electron microscopy in two mosses, Tortula latifoliaBruch and Tortula papillosa Wils. The gemmae develop on theadaxial surface of mature leaves from single initial cells onboth the lamina and costa in T. latifolia but only on the costain T. papillosa . Elongation of the initial cell is associatedwith the deposition of a highly extensible new wall whilst theold wall and cuticle in the apical dome rupture. The first divisionis transverse and separates a short basal cell embedded in thefoliar tissue and a distal cell, or gemma primordium, protrudingfrom the leaf surface. Subsequent divisions of the gemma primordiumgive rise to a six-to-eight-celled globose gemma with mucilaginousouter walls. During gemma development the basal cell producesa new wall and elongates again whilst the common wall with thegemma splits apart centripetally along the boundary betweenthe old and new wall in the basal cell; plasmodesmal connectionsare gradually severed and eventually the young gemma remainsconnected to the basal cell only by mucilage. After separationof the first-formed gemma, the basal cell may expand and producea second gemma by the same mechanism. The whole process maybe repeated several times resulting in the formation of a chainof gemmae stuck together by mucilage and which are liberatedonly when the leaves are fully hydrated. Accumulation of abundantlipid deposits in the gemmae after symplasmic isolation reflectsconsiderable photosynthetic autonomy. Abscission; bryophytes; cell wall formation; plasmodesmata; vegetative reproduction     

Lymphatic bed of the muscular sheath of the small intestine in animals and man during ontogenesis]

In the anatomy of the lymphatic bed of the small intestine muscle layer still there are obscure questions on the phylo- and ontogenesis of man and animals. Under study were 92 corpses (35 men, 27 cats and 30 dogs) of different age, beginning from the intrauterine period to old age. Different methods were used: polychromatic injection; macro- and microscopic dissection; staining after van Gieson and with haematoxilineeosin; impregnation with 0,25-1% solution of silver nitrate; dehydration and clearing; counting of the density of loops per a mm2 and the depth of their disposition in the intestinal wall with an ocular-micrometer. It was shown that formation of the lymph capillaries and their network in cats, dogs and man began from the end of the intrauterine period, was completed in new-borns and became sufficiently developed in young age. The structure of the lymph capillary networks is closely connected with the development of the muscle layer of the small intestine. Formation of the lymph lacunas begins after birth. With age the lymph capillary network becomes looser, the loops break and their size enlarges.     

The mycelial wall of Trichophyton mentagrophytes; ultrastructural study of its constitutive layers following the use of a method to demonstrate polysaccharides]

The ultrastructure of T. mentagrophytes hyphal walls was studied after the use of a cytochemical reaction for polysaccharides. The sections showed a wall composed of 3 layers viz: an external, poorly reactive one with a microfibrillary structure; a medium, fairly reactive one, with a periodic structure and an internal, intensivly stained layer, not observed in old cells. Other observations suggested that the septal medium layer should be differentiated from those cited above. The results are compared with previous data and a synthetic scheme of the Trichophyton mentagrophytes hyphal wall is proposed.     

Decreased response with age of the cardiac catecholamine sensitive adenylate cyclase system

The cardiac β-adrenergic coupled adenylate cyclase system was examined in young and old male Wistar rats. The concentration of binding sites for (?) ³H-DHA in membranes prepared from cardiac ventricles was 21.1 ± 2.78 (SD) fmoles/mg protein in 3–4 month old rats (young rats) and 31.2 ± 2.20 fmoles/mg protein in 24 month old rats (old rats). The dissociation constant, K_D was 4.3 ± 1.8 nM and 6.7 ± 1.7 nM for young and old rats, respectively. Various compounds were used to study the characteristics of activation of adenylate cyclase in homogenates from cardiac ventricles. Basal adenylate cyclase was reduced 30% in old animals compared to young (6.1 pmoles/min/mg protein in 24 month vs. 8.6 pmoles/min/mg protein in 3–4 month). (?)Isoproterenol (10^?5M) alone stimulated adenylate cyclase greater than two-fold in young rats (10.6 pmoles/min/mg protein above basal) and this stimulation was 34% lower in old animals. GppNHp (100 μM), fluoride (10 mM), and forskolin (100 μM) activation of adenylate cyclase above basal was reduced 38, 37, and 34%, respectively, in the old animals. No significant changes between the two groups were noted in the apparent affinity of GppNHp either alone or in the presence of (?)isoproterenol nor in the affinities of catecholamine agonists for activation of cyclase. These results suggest a reduction in the amount of functional regulatory protein or possibly cyclase in 24 month old rat ventricular tissue compared to 3–4 month old tissue. However, this data does not rule out the possibility of altered molecular interactions of a full complement of regulatory protein (s) with β-adrenergic receptor and/or catalytic adenylate cyclase.     

Heterogeneity of keratin distribution in the oral mucosa and skin of mammals as determined using monoclonal antibodies

Summary The immunohistochemical localization of keratins in the oral epithelia of several mammals was investigated using the monoclonal antibodies to keratins, PKK1 (41–56 kilodaltons) and KL1 (55–57 kilodaltons). The staining patterns obtained in different locations of the oral mucosa and of the skin epidermis were compared. In the papillae on the dorsal surface of the tongue, some areas exhibited marked PKK1 staining, while other area were PKK1 negative. In general, rodent oral epithelia were negative for PKK1 in the basal layer, while comparatively strong PKK1 staining was observed in cells of the upper spinous layer. In the epidermis, positive PKK1 reactions were confined to the basal layer, while KL1 staining was occasionally seen in the basal layer of oral epithelia. In cats, dogs, and monkeys, different PKK1 and KL1 binding patterns were observed in oral epithelia. Also, the distribution in oral epithelia differed from that seen in the epidermis of these animals. In the epidermis, the distribution of PKK1 and KL1 was regular, with PKK1 usually being confined to the basal layer, while KL1 binding was found in the spinous and granular cell layers, and was dependent on the degree of keratinization. In the animals studies, keratin expression as detected by PKK1 and KL1-was different in the skin epidermis and oral epithelia, and the localization of these keratins differed in the various types of oral mucosa.     

Hyperglycemia and loss of ovarian hormones mediate atheroma formation through endothelial layer disruption and increased permeability

The overall goal of this project was to examine the interactions of hyperglycemia and loss of ovarian hormones on the artery wall in a type I diabetic mouse model. Intact or ovariectomized (OVX) female BALB/C mice were fed a high-cholesterol diet. Half the animals were treated with steptozotocin to induce insulin-deficient diabetes mellitus, generating four treatment groups: control, intact; control, ovariectomized; diabetic, intact; diabetic, ovariectomized (DOVX). We examined arterial structure and function and found that 1) diabetes and ovariectomy additively increased endothelial layer permeability, 2) arterial stiffening was increased in DOVX, 3) DOVX synergistically increased atheroma formation, and 4) ultrastructural evaluation revealed that the basal lamina was often multilayered and formed convoluted aggregates separating endothelium from the internal elastic lamina in diabetic, but not control arteries or arteries from OVX mice. Endothelium overlying these regions formed thin cytoplasmic extensions between these aggregates and was often separated from the basal lamina by electron lucent spaces. Our studies showed that diabetes and loss of ovarian function have additive and synergistic effects to worsen arterial pathophysiology by disrupting the arterial endothelial layer with increased permeability and increased atheroma formation.