Oviducal Contribution to Alteration of the Vitelline Coat in the Frog, Rana japonica. An Electron Microscopic Study

The vitelline coat (VC) surrounding coelomic eggs of the frog, Rana japonica , comprises bundles of filaments running both parallel and perpendicular to the egg surface. The coat gives little or no staining reaction with PA-CrA-Silver methenamine. In contrast, in the VC of uterine eggs the filament bundles are less conspicuous. and the interstices between the filament bundles stain strongly for carbohydrate. This alteration occurs during passage of the eggs down the first 1/20 th of the oviduct, the pars recta. The epithelium of the p. recta contains secretory cells, which contain electron-dense granules distinct from those in the jelly-secreting cells in more caudal portions of the oviduct. Treatment of coelomic eggs with an extract of p. recta followed by exposure to a sperm suspension resulted in marked swelling and softening of the VC. These results indicate that the contents of the granules secreted from the epithelial cells in the p. recta are deposited in the VC to increase its susceptibility to a fertilizing sperm.     

Expression of cycloheximide resistance in carrot somatic hybrids and their segregants

Cycloheximide resistance (CH^r) was shown to be a function expressed in differentiated plant tissues, but not in unorganized callus tissues. A variant, WCH105, expressing CH^r in the callus, as well as in regenerated plantlets, was isolated from a cell line derived from a wild carrot plant. The plantlets regenerated from WCH105 are green, but do not produce normal, dissected leaves. Protoplasts of WCH105 were fused with that of a cycloheximidesensitive (CH^s) cell line derived from an albino, domesticated carrot. Hybrid selection was based on (1) irreversible growth inhibition of WCH105 protoplasts by iodacetamide, and (2) restoration of green plants producing dissected leaves.——Analysis of the CH^r trait as an unselected marker in the callus cells of the somatic hybrids indicated that it behaved as a recessive. The combined recessive and resistant phenotype of this trait allowed the recovery of CH^r segregants from CH^s hybrids at a frequency of 10^-4, 1000 times higher than the spontaneous frequency of CH^r. The recovery of CH^r somatic segregants confirmed the recessiveness of the CH^r trait.     

Theoretical and experimental studies on viscoelastic properties of erythrocyte membrane.

The deformation of a portion of erythrocyte during aspirational entry into a micropipette has been analyzed on the basis of a constant area deformation of an infinite plane membrane into a cylindrical tube. Consideration of the equilibrium of the membrane at the tip of the pipette has generated the relation between the aspirated length and the dimensionless time during deformational entry as well as during relaxation after the removal of aspiration pressure. Experimental studies on deformation and relaxation of normal human erythrocytes were performed with the use of micropipettes and a video dimension analyzer which allowed the continuous recording of the time-courses. The deformation consisted of an initial rapid phase with a membrane viscosity (range 0.6 x 10(-4) to 4 x 10(-4) dyn.s/cm) varying inversely with the degree of deformation and a later slow phase with a high membrane viscosity (mean 2.06 x 10(-2) dyn.s/cm) which was not correlated with the degree of deformation. The membrane viscosity of the recovery phase after 20 s of deformation (mean 5.44 x 10(-4) dyn.s/cm) was also independent of the degree of deformation. When determined after a short period of deformation (e.g., 2 s), however, membrane viscosity of the recovery phase became lower and agreed with that of the deformation phase. These results suggest that the rheological properties of the membrane can undergo dynamic changes depending on the extent and duration of deformation, reflecting molecular rearrangement in response to membrane strain.     

Cell Wall Solubilization in Pedicel Abscission of Begonia Flower Buds

Effects of metabolic inhibitors and growth regulators on the course of abscission and on the activities of cell wall solubilizing enzymes were studied in pedicel explants of Begonia flower buds. Actinomycin D, chloramphenicol and 2,4-dinitrophenol slightly retarded abscission, whereas cycloheximide exerted a strong inhibition if applied until 10.5 h after explant excision. Indoleacetic acid retarded and ethylene promoted abscission and cell wall solubilization. However, the activities of cell wall solubilizing enzymes did not correspond with the course of abscission. No polygalacturonase and pectic acid and pectin transeliminases could be detected in the abscission zone during abscission, whereas a low pectin methylesterase activity did not change. Endo- and exocellulase activities did not increase until about 10 h after the onset of abscission, indicating that they are the result rather than the cause of abscission.     

Hormonal Regulation of Pedicel Abscission in Begonia Flower Buds

In order to analyse the hormonal regulation of flower bud shedding in Begonia, levels of indoleacetic acid (IAA), abscisic acid (ABA) and ethylene were determined in buds and pedicels. The translocation and metabolism of ¹⁴C-labeled IAA in pedicel segments were also studied. In a monoecious Begonia fuchsioides hybrid, abscising male flower buds contain about 1% of the IAA present in non-abscising female flowers. In a male Begonia davisii hybrid, the seasonal variation in bud drop coincides with changes in the IAA content of the buds, while also the release of IAA from the bud to the pedicel is hampered. Abscission zones of these pedicels always contain abscission promoting ethylene concentrations. The tissue is prevented from responding with abscission by IAA from the flower buds. The buds also contain ABA but without influencing abscission considerably. Pretreatment with ethylene or ABA does not affect IAA transport in pedicel segments. The rate of this transport is 4–6 mm × h^–1:; the capacity increases with the transverse area. In young segments, IAA is decarboxylated and also otherwise metabolized.     

The reaction mechanisms and substrate-stereospecificities of L-alloisocitrate dehydrogenase and oxalosuccinate decarboxylase

A sequential reaction was suggested for the conversion of L-alloisocitrate to alpha-oxoglutarate by an enzyme complex of L-alloisocitrate dehydrogenase and oxalosuccinate decarboxylase from Pseudomonas strain No. 2, during which oxalosuccinate was not released from the enzyme-substrate complex. The stereochemistry of oxalosuccinate formed by L-alloisocitrate dehydrogenase and decarboxylated by oxalosuccinate decarboxylase was opposite to that of the substrate for D-isocitrate dehydrogenase. Incubation of L-alloisocitrate with the dehydrogenase and decarboxylase in deuterium oxide provided [3-2H]-alpha-oxoglutarate, the configuration of which turned out to be the same as that produced by D-isocitrate dehydrogenase from D-isocitrate. The data suggested that enol form of alpha-oxoglutarate was involved as an intermediate in decarboxylation of oxalosuccinate by oxalosuccinate decarboxylase. L-Alloisocitrate dehydrogenase was shown to react with pro-S proton of NADH.     

Allyl Isothiocyanate Ameliorates Angiogenesis and Inflammation in Dextran Sulfate Sodium-Induced Acute Colitis

Allyl isothiocyanate (AITC) is a phytochemical found in cruciferous vegetables that has known chemopreventive and chemotherapeutic activities. Thus far, the antiangiogenic activity of AITC has not been reported in in vivo studies. Herein, we investigated the effect of AITC on angiogenesis and inflammation in a mouse model of colitis. Experimental colitis was induced in mice by administering 3% dextran sulfate sodium via drinking water. To monitor the activity of AITC in this model, we measured body weight, disease activity indices, histopathological scores, microvascular density, myeloperoxidase activity, F4/80 staining, inducible nitric oxide synthase (iNOS) expression, cyclooxygenase-2 (COX-2) expression, and vascular endothelial growth factor (VEGF)-A/VEGF receptor 2 (VEGFR2) expression in the mice. We found that AITC-treated mice showed less weight loss, fewer clinical signs of colitis, and longer colons than vehicle-treated mice. AITC treatment also significantly lessened the disruption of colonic architecture that is normally associated with colitis and repressed the microvascularization response. Further, AITC treatment reduced both leukocyte recruitment and macrophage infiltration into the inflamed colon, and the mechanism these activities involved repressing iNOS and COX-2 expression. Finally, AITC attenuated the expression of VEGF-A and VEGFR2. Thus, AITC may have potential application in treating conditions marked by inflammatory-driven angiogenesis and mucosal inflammation.     

Computational Study on Subdural Cortical Stimulation - The Influence of the Head Geometry,Anisotropic Conductivity,and Electrode Configuration

Subdural cortical stimulation (SuCS) is a method used to inject electrical current through electrodes beneath the dura mater, and is known to be useful in treating brain disorders. However, precisely how SuCS must be applied to yield the most effective results has rarely been investigated. For this purpose, we developed a three-dimensional computational model that represents an anatomically realistic brain model including an upper chest. With this computational model, we investigated the influence of stimulation amplitudes, electrode configurations (single or paddle-array), and white matter conductivities (isotropy or anisotropy). Further, the effects of stimulation were compared with two other computational models, including an anatomically realistic brain-only model and the simplified extruded slab model representing the precentral gyrus area. The results of voltage stimulation suggested that there was a synergistic effect with the paddle-array due to the use of multiple electrodes; however, a single electrode was more efficient with current stimulation. The conventional model (simplified extruded slab) far overestimated the effects of stimulation with both voltage and current by comparison to our proposed realistic upper body model. However, the realistic upper body and full brain-only models demonstrated similar stimulation effects. In our investigation of the influence of anisotropic conductivity, model with a fixed ratio (1∶10) anisotropic conductivity yielded deeper penetration depths and larger extents of stimulation than others. However, isotropic and anisotropic models with fixed ratios (1∶2, 1∶5) yielded similar stimulation effects. Lastly, whether the reference electrode was located on the right or left chest had no substantial effects on stimulation.     

Ablation of Gadd45β ameliorates the inflammation and renal fibrosis caused by unilateral ureteral obstruction

The growth arrest and DNA damage‐inducible beta (Gadd45β) protein have been associated with various cellular functions, but its role in progressive renal disease is currently unknown. Here, we examined the effect of Gadd45β deletion on cell proliferation and apoptosis, inflammation, and renal fibrosis in an early chronic kidney disease (CKD) mouse model following unilateral ureteral obstruction (UUO). Wild‐type (WT) and Gadd45β‐knockout (KO) mice underwent either a sham operation or UUO and the kidneys were sampled eight days later. A histological assay revealed that ablation of Gadd45β ameliorated UUO‐induced renal injury. Cell proliferation was higher in Gadd45β KO mouse kidneys, but apoptosis was similar in both genotypes after UUO. Expression of pro‐inflammatory cytokines after UUO was down‐regulated in the kidneys from Gadd45β KO mice, whereas UUO‐mediated immune cell infiltration remained unchanged. The expression of pro‐inflammatory cytokines in response to LPS stimulation decreased in bone marrow‐derived macrophages from Gadd45β KO mice compared with that in WT mice. Importantly, UUO‐induced renal fibrosis was ameliorated in Gadd45β KO mice unlike in WT mice. Gadd45β was involved in TGF‐β signalling pathway regulation in kidney fibroblasts. Our findings demonstrate that Gadd45β plays a crucial role in renal injury and may be a therapeutic target for the treatment of CKD.