Bimodal (Taste/Tactile) Fibers Innervate the Maxillary Barbel in the Channel Catfish

Analysis of single fibers isolated from a branch of the facial/trigeminalcomplex innervating the maxillary barbel of the channel catfish,Ictalurus punctatus, indicated the existence of bimodal (taste/tactile)fibers. Of the 60 single fibers recorded, 14 (23%) respondedto both taste (amino acid) and tactile stimulation, 43 (72%)were responsive to only tactile stimulation and three (5%) respondedonly to taste stimulation. Quinine hydrochloride at a concentrationof 1.0 mM suppressed the mechanosensory activity of the bimodalfibers, but had no effect on the tactile-only fibers. Chem.Senses 22: 477–482, 1997. ¹Current address: Department of Otolaryngology, Kagoshima UniversityMedical School, 8-35-1 Sakuragaoka, Kagoshima 890, Japan ²Current address: Department of Oral Physiology, Ohu UniversitySchool of Detistry, 31-1 Misumido, Tomita, Koriyama, Fukushima963, Japan     

Modification of chemical properties of cell wall polysaccharides in the inner tissues by white light in relation to the decrease in tissue tension in Pisum sativum epicotyls

When white light irradiation inhibits shoot growth in derooted pea ( Pisum sativum L. cv. Alaska) cuttings, it decreases tissue tension, a driving force for shoot growth, by making the cell wall of the inner tissues mechanically rigid. To elucidate the mechanism by which light affects the mechanical properties of the cell wall in the inner tissues, its effect on the chemical properties of the cell walls was studied by analyzing qualitatively and quantitatively cell wall polysaccharides in the epdidermis and inner tissue of pea epicotyls grown in both dark and light. The amount of polysaccharides per subhook in the cell walls of both tissues increased during a 4-h dark incubation. Light suppressed the increase in hemicellulosic (HC)-II and cellulosic polysaccharides in the inner tissues, while it did not affect the increase in other wall fractions in either the epidermal or subepidermal tissues. No light effect was observed on the neutral sugar compositions of pectin, HC-I or HC-II fractions in either of the tissues. Light increased the mass-average molecular mass of xyloglucan and rhamnoarabinogalactan in HC-II fractions in the inner tissues, while such an effect was not observed in the epidermis. These facts suggest that the light-induced decrease in the tissue tension in pea epicotyls is caused by an increase in the molecular size of xyloglucan, rhamnoarabinogalactan in the HC-II fraction and/or the suppression of the synthesis of HC-II and cellulosic polysaccharides in the inner tissues.     

Antifungal activity ofBullera alba (Hanna) Derx

A strain ofBullera alba that secretes a killer toxin inhibitory (at pH values ranging from 3 to 7) to many ascomycetous and basidiomycetous yeast-like fungi was discovered. Its killer phenotype was incurable. The toxin was relatively thermostable and resistant to many proteases, and it was identified as a microcin. It inhibited the growth of some pathogenic yeasts and was the most active againstCryptococcus neoformans.     

Is water immersion useful for analyzing gravity resistance responses in terrestrial plants?

Water immersion has been used as a simulator of microgravity for analyzing gravity responses in semiaquatic plants such as rice. To examine whether or not water immersion for a short experimental period is a useful microgravity simulator even in terrestrial plants, we analyzed effects of water immersion on the cell wall rigidity and metabolisms of its constituents in azuki bean epicotyls. The cell wall rigidity of epicotyls grown underwater was significantly lower than that in the control. Water immersion also caused a decrease in molecular mass of xyloglucans as well as the thinning of the cell wall. Such changes in the mechanical and chemical properties of the cell wall underwater were similar to those observed in microgravity conditions in space. These results suggest that water immersion for a short period is a useful system for analyzing gravity resistance responses even in terrestrial plants.     

Vertical distribution, population structure and life history of Thysanoessa longipes (Crustacea: Euphausiacea) around Yamato Rise, central Japan Sea

The diel vertical migration, growth and spawning season of theeuphausiid, Thysanoessa longipes, were investigated using seasonalsamples collected from waters around the Yamato Rise, centralJapan Sea, during the period 1987 to 1999. Thysanoessa longipeswas present throughout a broad bathymetric layer extending downas deep as 1000 m. There was a clear trend for larger specimensto occur at deeper depths. The peak of abundance of the totalpopulation occurred at depths of 30–300 m at night, and150–500 m during the day, and the distance of the dielvertical migrations of the total population was estimated tobe between 100 and 150 m. Population structure analysis revealedthe occurrence of three cohorts aged 0+, 1+ and 2+ years, withfemales attaining a larger body size than males. Growth as determinedby body length was found to fit well to the von Bertalanffygrowth equation. The estimated life span for males and femalesis 3 years, and females reach maturity in 2 years. Based onthe occurrence of calyptopis larvae, spawning of T. longipeswas estimated to occur over only a limited period of the yearbetween April and May.     

Ontogenetic Vertical Migration and Life cycle of Neocalanus Plumchrus (Crustacea: Copepoda) in the Oyashio Region, with Notes on Regional Variations in Body Sizes

The ontogenetic vertical migration and life cycle of Neocalanusplumchrus were investigated by anal-yzing monthly populationstructure at Site H in the Oyashio region from September 1996through October 1997. Additional sampling was also done at severalstations covering the entire subarctic Pacific, Okhotsk Seaand Japan Sea as a basis for regional comparison of life cyclesand body sizes. At Site H, N. plumchrus spawned October to Aprilbelow 250 m depth. Young copepodite stages (C1–C5) occurredduring June late in the phytoplankton bloom. The C5 migratedto the deeper layers in July–August where they moltedto adults. Development time of C5 to C6 was highly variable.The ontogenetic vertical migration of N. plumchrus ranged fromthe surface to 1000–2000 m depth, and the life cycle wasannual. Temporal data on population structure and vertical distributionsuggestedthe annual life cycle was generally synchronized throughoutthe subarctic Pacific and its marginal seas. Geographical comparisonof C5 prosome length indicated the occurrence of significantlylarge specimens in the Oyashio region and Okhotsk Sea but smallspecimens in the Japan Sea. Possible causes for regional variabilityin body sizes are discussed.     

Prevalence and Characteristics of eae-Positive Escherichia coli from Healthy Cattle in Japan

The prevalence of eae-positive Escherichia coli (eaeEC) in Japan was examined using rectal stool samples taken from 35 calves less than 1 month old, 107 calves more than 1 to 3 months old, 88 heifers more than 3 to 6 months old, 214 heifers over 6 months old, and cows from 95 farms. Screening with eae PCR revealed the prevalence to be, with increasing age, 31.4, 8.4, 26.1, and 14.5%, respectively. Of 51 selected eaeEC strains, more than 40% were serotyped as O26, O103, O111, O145, or O157, which are frequently detected as enterohemorrhagic E. coli types. Four strains were identified as recently reported intimin types η, ι, and κ.     

Modification of cell wall architecture of wheat coleoptiles grown under hypergravity conditions.

Cell wall structure of wheat coleoptiles grown under continuous hypergravity (300 g) conditions was investigated. Length of coleoptiles exposed to hypergravity for 2-4 days from germination stage was 60-70% of that of 1 g control. The amounts of cell wall polysaccharides substantially increased during the incubation period both in 1 g control and hypergravity-treated coleoptiles. As a results, the levels of cell wall polysaccharides per unit length of coleoptile, which mean the thickness of cell walls, largely increased under hypergravity conditions. The major sugar components of the hemicellulose fraction, a polymer fraction extracted from cell walls with strong alkali, were arabinose (Ara), xylose (Xyl) and glucose (Glc). The molar ratios of Ara and Xyl to Glc in hypergravity-treated coleoptiles were higher than those in control coleoptiles. Furthermore, the fractionation of hemicellulosic polymers into the neutral and acidic polymers by the anion-exchange column showed that the levels of acidic polymers in cell walls of hypergravity-treated coleoptiles were higher than those of control coleoptiles. These results suggest that hypergravity stimuli bias the synthesis of hemicellulosic polysaccharides and increase the proportion of acidic polymers, such as arabinoxylans, in cell walls of wheat coleoptiles. These structural changes in cell walls may contribute to plant resistance to hypergravity stimuli.