Postembryonic development of the complex tibial organ in the foreleg of the bushcricket Ephippiger ephippiger (Orthoptera,Tettigoniidae)

Summary The postembryonic development of the morphology and anatomy of the complex tibial organ in the foreleg of the bushcricket Ephippiger ephippiger is described. All the receptor cells are present in the subgenual organ, the intermediate organ and the crista acustica in the 1st larval instar. Generally, even in the 1st instar, the arrangement of the scolopidia in the three organs resembles the adult structure. The acoustic trachea, the tympana, the tympanal covers and the acoustic spiracle develop step by step in subsequent instars. The acoustic trachea resembles the adult structure for the first time in the 4th instar, although its volume is still small. The auditory threshold curves recorded from the tympanal nerve in instars 4, 5 and 6 show the same frequency maxima as those in the adult. The overall sensitivity significantly increases after the final moult. The dimensions of structures that lie within the crista acustica and that are probably involved in stimulus transduction and in frequency tuning have been analysed. The dorsal wall of the anterior trachea, the tectorial membrane and the cap cells have similar dimensions, especially in the last three instars and in adults.     

Characteristics of dynamic postural reactions in the locust hindleg

Summary The use of the locust (Schistocerca americana) hindleg in postural control was examined in animals that stood on a repeatedly swayed vertical substrate. Myograms were recorded from leg muscles and the angle of the femoro-tibial joint was monitored photographically. Two discrete strategies were observed,; in compensatory reactions the hindleg was held in place, while in flexion reactions, the leg was moved, most often to complete flexion of the femoro-tibial joint. Tightly coupled, rhythmic bursting occurred in the flexor and levator muscles of the leg during compensatory reactions. Bursting was initiated repeatedly when the substrate was being pulled away from the animal. Bursting was correlated with subsequent decreases in the rate of change of the femorotibial joint angle. Compensatory and flexion reactions occurred preferentially in different ranges of joint angles: most often, compensatory reactions occurred in the midrange, while flexion reactions were elicited in the extremes of joint angle. These differences may be due to the mechanical advantages of the tibial muscles and the leg may be moved to full flexion because of a locking mechanism of the flexor muscle tendon. These reactions are compared with known reflexes of hindleg proprioceptors and contrasted with similar responses of vertebrates.     

外侧臂旁核神经元对穹隆下器逆向刺激和孤束核顺向刺激的反应

细胞外记录大鼠外侧臂旁核(LPBN)神经元单位放电,观察了刺激穹隆下器(SFO)在记录单位诱发的逆向反应和静脉注射新福林兴奋外周压力感受器和刺激孤束核(NTS)减压区诱发的顺向反应。实验发现:刺激 SFO,9.9%(15/151)的 LPBN 神经元有逆向反应。静脉注射新福林,40.7%(22/54)的 LPBN 神经元有抑制反应,27.8%(17/54)有兴奋反应。刺激 NTS,55.6%(94/169)的 LPBN 神经元呈现顺向兴奋反应;22.5%(38/169)呈现顺向抑制反应。观察静脉注射新福林对 SFO 刺激有逆向反应的 LPBN 神经元自发放电的影响,在两个受试单位均见抑制反应。观察刺激 NTS 对逆向反应单位自发放电的影响,在8个受试单位中,6个呈兴奋反应;2个呈抑制反应。以上结果表明:LPBN 接受来自 NTS 的兴奋性或抑制性压力感受性传入,并把这种信息经 LPBN-SFO 直接通路传输到 SFO。     

Ultrastructure of the frontal organ in Convoluta and Macrostomum spp.: significance for models of the turbellarian archetype

Present models of turbellarian evolution depict the organism with a frontal organ — a complex of glands whose necks emerge at the anterior tip of the body — and therefore imply that this organ is homologous throughout the Turbellaria. However, comparisons of representatives of the Acoela and Macrostomida, two putatively primitive orders of the Turbellaria, show that frontal organs in these two are not similar in ultrastructure or histochemistry. The acoel Convoluta pulchra had a prominent cluster of frontal mucous glands whose necks emerged together in a frontal pore at the exact apical pole of the organism, and an array of smaller glands of at least five other types opened at the anterior end, separately from and ventral to this pore. The frontal organs (Stirndrüsen) of two species of Macrostomum on the other hand, comprised an array of discretely emerging necks of at least two gland types including one with rhabdiform (rhammite) and one with globular mucous secretion granules neither of which emerge at the apical pole. In neither species did the organ appear to be sensory. Our findings indicate a low probability of homology between the frontal glands of the Acoela and Macrostomida.     

Acetylcholine, ATP, and Proteoglycan Are Common to Synaptic Vesicles Isolated from the Electric Organs of Electric Eel and Electric Catfish as Well as from Rat Diaphragm

Cholinergic synaptic vesicles were isolated from the electric organs of the electric eel (Electrophorus electricus) and the electric catfish (Malapterurus electricus) as well as from the diaphragm of the rat by density gradient centrifugation followed by column chromatography on Sephacryl-1000. This was verified by both biochemical and electron microscopic criteria. Differences in size between synaptic vesicles from the various tissue sources were reflected by their elution pattern from the Sephacryl column. Specific activities of acetylcholine (ACh; in nmol/mg of protein) of chromatography-purified vesicle fractions were 36 (electric eel), 2 (electric catfish), and 1 (rat diaphragm). Synaptic vesicles from all three sources contained ATP in addition to ACh (molar ratios of ACh/ATP, 9-12) as well as binding activity for an antibody raised against Torpedo cholinergic synaptic vesicle proteoglycan. Synaptic vesicles from rat diaphragm contained binding activity for the monoclonal antibody asv 48 raised against a rat brain 65-kilodalton synaptic vesicle protein. Antibody asv 48 binding was absent from electric eel and electric catfish synaptic vesicles. These antibody binding results, which were obtained by a dot blot assay on isolated vesicles, directly correspond to the immunocytochemical results demonstrating fluorescein isothiocyanate staining in the respective nerve terminals. Our results imply that ACh, ATP, and proteoglycan are common molecular constituents of motor nerve terminal-derived synaptic vesicles from Torpedo to rat. In addition to ACh, both ATP and proteoglycan may play a specific role in the process of cholinergic signal transmission.     

The possible involvement of polyamines in the development of tomato fruits in vitro

The apparent involvement of ornithine decarboxylase (ODC) and putrescine in the early stages of fruit growth in tomato (Lycopersicon esculentum Mill.) has been previously described. Further evidence presented here supports the direct involvement of ODC and putrescine in the cell division process in tomato fruits. In tomato fruits grown in vitro, in which basic growth processes are inhibited, the activity of ODC and arginine decarboxylase (ADC) and the level of free polyamines were reduced. While ODC and ADC activity was correlated with the period of cell division in the tomato fruit, the free polyamine content was correlated with the DNA content, cell size, and fruit fresh weight. The addition of exogenous putrescine, however, did not restore the basic growth processes in the fruits grown in vitro.     

Distribution of neurotensin-like immunoreactivity in rat and cat area postrema

The distribution of neurotensin-like immunoreactive (NT-LI) fibers and cell bodies in the area postrema (AP) of rat and cat, utilizing the peroxidase, antiperoxidase (PAP) technique, is described. In the rat, the greatest accumulation of NT-LI fibers were present along the borders of the AP, while there were very few NT-LI fibers in central regions. In the cat, scattered NT-LI fibers occupied the majority of the central AP, while moderate numbers of NT-LI fibers were present at the ventromedial border. In more rostral cat AP levels, the number of NT-LI fibers decreased. NT-LI somata were present in rat AP, but were lacking in cat AP. The localization of NT within the AP suggests that the cardiovascular and gastric effects attributed to NT may be mediated, in part, through the AP.     

Osmotic control of luminescence and growth in Photobacterium leiognathi from ponyfish light organs

Osmolarity was found to control the luminescence and growth of Photobacterium leiognathi strain LN-1a isolated from the light organ of the ponyfish Leiognathus nuchalis (family Leiognathidae). Low osmolarity (ca. 400 mOsm) stimulated luminescence per cell 80 to 100-fold to a level (ca. 2.0×10⁴ quanta·s^-1·cell^-1) equal to that of bacteria taken directly from the light organ and increased the level of luciferase per cell 8 to 10-fold compared to high osmolarity (ca. 800 mOsm). Conversely, high osmolarity stimulated oxygen uptake and growth rate 2 to 4-fold compared to low osmolarity. Of 21 additional tested strains of P. leiognathi from light organs of 9 other ponyfish species, all responded similarly. Low osmolarity may be a host control factor that functions to stimulate the luminescence and restrict the growth of ponyfish light organ bacteria in situ.     

Functional and ultrastructural effects of nontypeable haemophilus influenzae in a hamster trachea organ culture system

Summary A hamster trachea organ culture system was utilized to evaluate quantitatively the effects of a strain of nontypeableHaemophilus influenzae (NTHI) and culture supernatants of the same strain on ciliary activity. Tracheal explants were maintained in organ culture for 96 to 144 h and ciliary activity was observed daily with an inverted microscope. Explants continuously exposed to a strain of NTHI had a progressive decline in ciliary activity which was significantly lower than uninfected controls evaluated concomitantly by 48 h of exposure and thereafter. Histologic studies revealed a progressive degeneration of mucosal cells and exfoliation of ciliated cells. Scanning electron microscopy showed little adherence of NTHI to the mucosal surface. Sterile broth cultures of NTHI and supernatants of organ cultures infected with the same NTHI strain had no adverse effect on ciliary activity. Infected tracheal explants treated with ampicillin 24, 48, or 72 h after continuous bacterial challenge had no significant decline in ciliary activity compared to controls. The lack of adherence and the histologic changes observed when hamster trachea cultures were infected with NTHI suggested a toxin might mediate the damage observed. Broth and organ culture supernatants, however, produced no damage. Therefore, further studies are needed to determine the role, if any, of a toxin in the production of damage to hamster tracheal explants by NTHI. This work was supported by a Merit Review grant from the Veterans Administration and by Grant AI-19641 from the National Institute of Allergy and Infectious Diseases.     

Concanavalin A-binding glycoproteins in the subcommissural and the pineal organ of the sheep (Ovis aries)

Summary Glycoproteins rich in mannosyl or glucosyl residues were analyzed in the subcommissural organ (SCO) and the pineal organ of the sheep (Ovis aries). By use of concanavalin A labelled with fluorescein isothiocyanate, fluorescent material was found both in ependymal and hypendymal cells of the SCO. In the pineal organ, either isolated or grouped parenchymal cells showed a marked fluorescence. These cells may correspond to ependymal elements also called interstitial cells or supporting cells. In addition, scarce slender, fluorescent processes were observed in the pineal parenchyma. The techniques of electrophoresis and electrotransfer on nitrocellulose paper have been applied to analyze the glycopeptide content of the SCO and the pineal organ in comparison to cerebellar and cerebral fractions solubilized by use of Triton X 100. Approximately 30 different concanavalin A-reactive glycopeptides were revealed in each fraction. In the SCO extract four glycopeptides (30, 54, 72, 100 kd) might correspond to subunits of the glycoprotein(s) characteristically stored in the ependymal cells of the SCO. In addition, two glycopeptides (32/33, 115 kd) are specific to the pineal organ extract. The possible similarity of the concanavalin A-reactive material in both organs is discussed and a putative secretory activity of the pineal ependymal cells is postulated.