Mechanical sensitivity of the facial nerve fibers innervating the anterior palate of the puffer,Fugu pardalis,and their central projection to the primary taste center

Mechanical and chemical sensitivity of the palatine nerve, ramus palatinus facialis, innervating the anterior palate of the puffer, Fugu pardalis, and their central projection to the primary taste center were investigated. Application of horseradish peroxidase (HRP) to the central cut end of the palatine nerve resulted in retrogradely labeled neurons in the geniculate ganglion but no such neurons in the trigeminal ganglion, suggesting that the palatine nerve is represented only by the facial component. Tracing of the facial sensory root in serial histological sections of the brain stem suggested that the facial sensory nerve fibers project only to the visceral sensory column of the medulla. Peripheral recordings from the palatine nerve bundle showed that both mechanical and chemical stimuli caused marked responses. Mechanosensitive fibers were rather uniformly distributed in the nerve bundle. Intra-cranial recordings from the trigeminal and facial nerves at their respective roots revealed that tactile information produced in the anterior palate was carried by the facial nerve fibers. Elimination of the sea water current over the receptive field also caused a marked response in the palatine nerve bundle or facial nerve root while this did not cause any detectable responses in the trigeminal nerve root. Single fiber analyses of the mechanical responsiveness of the palatine nerve were performed by recording unit responses of 106 single fibers to mechanical stimuli (water flow), HCl (0.005 M), uridine-5'-monophosphate (UMP, 0.001 M), proline (0.01 M), CaCl2 (0.5 M), and NaSCN (0.5 M). All these fibers responded well to one of the above stimuli; however, most taste fibers did not respond well to the inorganic salts. The palatine fibers (n = 36), identified as mechanosensitive, never responded to any of the chemical stimuli, whereas chemosensitive fibers (n = 70) did not respond to mechanical stimuli at all. The chemosensitive units showed a high specificity to the above stimuli: they tended to respond selectively to hydrochloric acid, UMP, or proline. The responses of the mechanosensitive units consisted of phasic and tonic impulse trains and the sensitivity of the units varied considerably. The results reveal that the facial nerve fibers innervating the anterior palate of the puffer contain two kinds of afferent fibers, chemosensory and mechanosensory respectively, and suggest that the convergence of the tactile and gustatory information first occurs in the neurons of the primary gustatory center in the medulla.     

The influence of aging on renal response to cadmium in Syrian hamsters

To determine the renal effects of cadmium (Cd) in older animals, we administered subcutaneously a single dose of cadmium, 3.0 mg/kg/BW, to Syrian hamsters aged 16 wk (“young”) and 60 wk (“old”). Marked morphologic changes in the kidney and renal dysfunction were observed, especially in the older animals. The concentration of MDA in the renal cortex was significantly increased only in young hamsters treated with cadmium. Concentrations of glutathione (GSH) in the renal cortex were increased in the old hamsters on d 6. Increased levels of renal MDA after cadmium treatment may induce the production of GSH in the kidney thus preventing renal damage. Aging can increase the susceptibility to the renal effects of cadmium.     

Excitation energy transfer in the green photosynthetic bacterium Chloroflexus aurantiacus: A specific effect of 1-hexanol on the optical properties of baseplate and energy transfer processes

The effect of 1-hexanol on spectral properties and the processes of energy transfer of the green gliding photosynthetic bacterium Chloroflexus aurantiacus was investigated with reference to the baseplate region. On addition of 1-hexanol to a cell suspension in a concentration of one-fourth saturation, a specific change in the baseplate region was induced: that is, a bleach of the 793-nm component, and an increase in absorption of the 813-nm component. This result was also confirmed by fluorescence spectra of whole cells and isolated chlorosomes. The processes of energy transfer were affected in the overall transfer efficiency but not kinetically, indicating that 1-hexanol suppressed the flux of energy flow from the baseplate to the B806-866 complexes in the cytoplasmic membranes. The fluorescence excitation spectrum suggests a specific site of interaction between bacteriochlorophyll (BChl) c with a maximum at 771 nm in the rod elements and BChl a with a maximum at 793 nm in the baseplate, which is a funnel for a fast transfer of energy to the B806-866 complexes in the membranes. The absorption spectrum of chlorosomes was resolved to components consistently on the basis, including circular dichroism and magnetic circular dichroism spectra; besides two major BChl c forms, bands corresponding to tetramer, dimer, and monomer were also discernible, which are supposed to be intermediary components for a higher order structure. A tentative model for the antenna system of C. aurantiacus is proposed.Abbreviations A670 a component whose absorption maximum is located at 670 nm - (B)Chl (bacterio)chlorophyll - CD circular dichroism - F675 a component whose emission maximum is located at 675 nm - FMO protein Fenna-Mathews-Olson protein - LD linear dichroism - LH light-harvesting - McD magnetic circular dichroism - PS photosystem - RC reaction center     

A soluble extract from human spermatozoa activates ascidian oocytes

A soluble extract from human spermatozoa induced calcium oscillations and extrusion of the first polar body when injected into oocytes of the ascidian Ciona intestinalis . The properties of calcium oscillations and time of polar body extrusion precisely mimic oocyte activation induced by C. intestinalis sperm or sperm extracts. The data suggest that human sperm extracts can activate oocytes of different phyla by the same mechanism as homologous spermatozoa. Injection of inositol 1,4,5-trisphosphate (IP₃) into C. intestinalis oocytes mimicked to some extent the initial stages of oocyte activation, but the results demonstrate that ascidian oocyte activation by human sperm extract cannot be explained solely in terms of IP₃-induced calcium release. Injection of other calcium releasing second messengers, cyclic adenosine diphosphate ribose, or calcium ions, does not lead to oocyte activation or release intracellular calcium in ascidian oocytes. It was concluded that human spermatozoa contain one or more molecules that can trigger intracellular calcium release in oocytes from different phyla.     

Future risk of the maize orange leafhopper,Cicadulina bipunctata,and maize wallaby ear symptom in temperate Japan

Since the 1980s, the maize orange leafhopper, Cicadulina bipunctata, has been gradually expanding its range in east Asia associated with global warming. This leafhopper induces maize wallaby ear symptom (MWES) on young maize plants and has become a threat to forage maize production in southern parts of temperate Japan since around 2000. In this study, using predictions of future temperature and precipitation calculated from Atmosphere–Ocean Coupled General Circulation Models, the future risk of C. bipunctata expansion and MWES occurrence in Japan (spatial resolution: 1 km²) was predicted. A nominal logistic regression analysis showed a significant contribution of cumulative low temperature during winter to the current distribution of C. bipunctata. The range of C. bipunctata was predicted to expand northward, particularly in Kyushu, Shikoku and the southern part of Honshu after the 2060s. Predicted intensification of MWES would reduce the efficacy of maize cultivars that are currently tolerant to MWES, in southern Kyushu in the 2020s, and in most parts of Kyushu, Shikoku and southwestern Honshu in the 2060s. These results suggest the need for measures to counter further expansion of C. bipunctata and improvement of current tolerant maize cultivars.     

Factors underlying genotypic differences in the induction of photosynthesis in soybean [Glycine max (L.) Merr.]

Crop leaves are subject to continually changing light levels in the field. Photosynthetic efficiency of a crop canopy and productivity will depend significantly on how quickly a leaf can acclimate to a change. One measure of speed of response is the rate of photosynthesis increase toward its steady state on transition from low to high light. This rate was measured for seven genotypes of soybean [Glycine max (L.) Merr.]. After 10 min of illumination, cultivar ‘UA4805’ (UA) had achieved a leaf photosynthetic rate (P_n) of 23.2 μmol · m^?2 · s^?1, close to its steady‐state rate, while the slowest cultivar ‘Tachinagaha’ (Tc) had only reached 13.0 μmol · m^?2 · s^?1 and was still many minutes from obtaining steady state. This difference was further investigated by examining induction at a range of carbon dioxide concentrations. Applying a biochemical model of limitations to photosynthesis to the responses of P_n to intercellular CO₂ concentration (C_i), it was found that the speed of apparent in vivo activation of ribulose‐1:5‐bisphosphate carboxylase/oxygenase (Rubisco) was responsible for this difference. Sequence analysis of the Rubisco activase gene revealed single nucleotide polymorphisms that could relate to this difference. The results show a potential route for selection of cultivars with increased photosynthetic efficiency in fluctuating light.     

A break on the Arrhenius plot of germination activity in rice seeds

The germination activity of rice seeds was estimated at a numberof different temperatures for varieties including both japonicaand indica types. A break was found on the Arrhenius plot ofgermination activity. The breaking temperature was approximately17?C, irrespective of the variety or the germination activityat 25?C. (Received November 21, 1974; )     

Molecular Construction of Clostridium botulinum Progenitor Toxin

Molecular dissociation of purified type F progenitor toxin with an S20,W of 10.3 and a molecular weight of 235,000 into two components, toxic and atoxic, was demonstrated by ultracentrifugation, gel filtration, and diethylaminoethyl-Sephadex chromatography at pH 7.5. The ultracentrifugal analysis indicated that type F progenitor toxin dissociates into components of the same molecular size of 5.9S. The toxic component contained a toxicity of 2.5 times 10-8 50% lethal doses per mg of N. Much higher stability of progenitor toxin than that of derivative toxin, particularly at pH below 5, suggests that only progenitor toxin can act as an oral toxin.     

Analysis of spatial association between two species based on the interspecies mean crowding

Summary and Conclusion The measurement of spatial association between two species is considered on the basis of interspecies mean crowding. Two indices of overlapping, γ andC _μ, are derived as geometric and weighted arithmetic means of the same component ratios related to inter- and intraspecies mean crowdings. Both indices behave in a similar way, ranging from 1 when the distributions of two species are completely overlapped to 0 when they are completely exclusive with each other. The former is essentially identical with indices proposed byKuno (1968) andPianka (1973), and the latter is a modified form ofMorisita’s (1959)C _δ index. Indices to measure the degree of spatial correlation between species, ω andR _μ, are then derived for both kinds of overlapping indices, which vary from 1 in complete overlapping, through 0 in independent occurrence, to −1 in complete exclusion. Various kinds of interspecies association are analyzed using these indices and an extended form of the regression graph which provides a convenient way of indicating the spatial interrelation between two species as well as distribution patterns of respective species. The method presented in this paper may also be applicable to compare temporal distribution patterns between species, similarity between communities, etc. For such a wider application which includes continuous as well as discrete distributions, the interpretation of intra- and interspecies mean crowdings is not necessarily appropriate, and hence the concept of mean concentration with the symbols and for intraspecies relation and and for interspecies relation is suggested. This study was supported by Science Research Fund (No. 148041) from the Ministry of Education.