Recording cerebellar neuron activities in swimming goldfish

ABSTRACT:   Neuronal activities were investigated in the cerebellum of immobilized and swimming goldfish Carassius auratus . Extracellularly recorded neural activities of the cerebellum in immobilized goldfish were characterized and classified into five types. Based on the waveforms and recording depths, these five neural activity types were estimated to originate from three identified classes of cerebellar neurons: Purkinje cells, eurydendroid cells, and granule cells. Chronic recording of cerebellar neuron activities in unrestrained goldfish was performed for more than 100 h. During the chronic recordings, a submersible amplifier attached to the goldfish head, and a multielectrode array developed for the present study were used. Neuronal activities in the cerebellum of free-swimming fish could also be classified into five types as in the immobilized condition. Firing patterns of two neurons identified as Purkinje cells and eurydendroid cells were analyzed during turning movements of the goldfish. The firing patterns of these neurons changed in relation to turning movements. Although some improvements are required, the chronic recording method developed in the present study can be applied to further investigations concerning the direct relationship between brain neural activities and certain behavior.     

Chemical and Thermal Properties of Freshwater Prawn (Macrobrachium rosenbergii) Meat

Chemical compositions and thermal properties of cultured freshwater prawn meat (FPM) were studied. FPM contained 83.2% protein (dry basis), 62.7% of which was myofibrillar protein. Pepsin-soluble collagen (PSC) and insoluble collagen (ISC) contents were 0.63 and 0.32%, respectively. Both collagens were similar to type V collagen from porcine placenta. Glutamic acid/glutamine, arginine, aspartic acid/?asparagine, and lysine were abundant amino acids in FPM. Glycine, proline, hydroxyproline, and aspartic acid/?asparagine were predominant in both collagens. FPM exhibited thermal transition temperatures (T_max) of 48.3 and 64.7°C, whereas T_max of PSC and ISC were 43.0 and 46.0°C, respectively. Textural changes in FPM during post-mortem storage on ice are plausibly dependent upon its compositional and thermal properties.     

Adenosine monophosphate degradation and inosinic acid accumulation in the shrimp Penaeus japonicus

International Aquatic Research - Shrimp muscle contains taste component compounds, such as glutamic acid and inosinic acid (IMP). When both are present, taste intensity increases by fourfold to...     

Cloning and expression of a surface immunogenic protein in Streptococcus dysgalactiae isolated from fish and its application in enzyme‐linked immunosorbent assays to diagnose S. dysgalactiae infections in fish

Lancefield group C Streptococcus dysgalactiae (GCSD) causes severe necrotic lesions in the caudal peduncle in the genus Seriola farmed in Japan. To develop a sero‐diagnostic method for GCSD infection in farmed fish, we attempted to identify a surface immunogenic protein that induces an antibody after infection with GCSD by immunoblot analysis using sera collected from infected fish. A protein obtained from sodium dodecyl sulfate (SDS) extracts of GCSD was identified as S. dysgalactiae surface immunogenic protein (Sd‐Sip). Sd‐Sip exhibited more than 94% homology with a surface antigen or a hypothetical protein from S. dysgalactiae mammalian isolates at the nucleotide sequence level. Expression of the recombinant Sd‐Sip (rSd‐Sip) was confirmed by immunoblot analysis, that is, its reactivity to GCSD‐infected sera. Antibody detection ELISA using rSd‐Sip and their usefulness for diagnosis of GCSD infection were examined. GCSD‐infected sera collected from farmed amberjack, Seriola dumerili (Risso), showed strong reaction with immobilized rSd‐Sip. Meanwhile, sera immunized by other pathogenic bacteria of fish were showed ELISA values similar to those of non‐infected sera. These results of this study suggest that the antibody detection ELISA using rSd‐Sip is an effective diagnostic method for GCSD infection in fish.     

Comparison in taste and extractive components of boiled dorsal muscle and broth from half-smooth golden puffer Lagocephalus spadiceus caught in Japan with those of the same fish imported

The taste and extractive components of boiled dorsal muscle and broth prepared from half-smooth golden puffer Lagocephalus spadiceus caught in Japan and from those imported from China were compared. In the sensory test, the first taste, elasticity, and saltiness of boiled muscle from Japanese (domestic) fish were higher than those of the imported fish, whereas the orthonasal fishy smell of the imported fish was higher than that of the domestic fish. The first taste, aftertaste, retronasal fishy smell, sweetness, saltiness, and umami of the broth prepared from dorsal muscle of the domestic fish were higher than those of the imported fish, whereas orthonasal fishy smell and bitterness of the imported fish were higher than those of the domestic fish. Most panelists preferred the overall taste of the domestic fish to that of the imported fish. The concentration of trimethylamine in the trichloroacetic acid extracts from boiled muscle and broth of the imported fish was higher than that of the domestic fish, suggesting that this substance contributes to the orthonasal fishy smell of the imported fish.     

Studies on the green liver in cultured red sea bream fed low level and non-fish meal diets: Relationship between hepatic taurine and biliverdin levels

SUMMARY: The aim of this study was to investigate the cause of green liver in red sea bream fed substitute protein diets. Red sea bream Pagrus major was given either of the following diets for 28 weeks: (1) control diet (50% fish meal), (2) low level fish meal diet (15% fish meal), and (3) non-fish meal diet (0% fish meal). The green liver was observed in all groups tested, but the incidence was much higher in the experimental diet groups. The feeding of substitute protein diets reduced plasma triglyceride and cholesterol levels. However, there was no significant difference in plasma hepatic enzyme activities and plasma bile salts concentration among the treatments. Fish fed the substitute protein diets showed low hepatic taurine levels with an appearance of a biliverdin in the liver. Moreover, the proportion of ditaurobilirubin to total biliary bile pigments was significantly lower in fish fed the substitute protein diets. These data indicate that feeding of substitute protein diets did not induce any cholestatic hepatobiliary obstructions and that the low hepatic taurine level was one of the probable factors responsible for the occurrence of green liver in red sea bream fed substitute protein diets.     

Metabarcoding of feces and intestinal contents to determine carnivorous diets in red-crowned cranes in eastern Hokkaido,Japan

The red-crowned crane Grus japonensis in Hokkaido, Japan forms a closed population as a residence that is independent of the mainland population. Based on observations of a limited number of individuals as well as cranes in captivity, red-crowned cranes are omnivores and eat fish, worms, insects and plants in their own territories except in winter, when they are fed with dent corn that is supplied in eastern Hokkaido. DNA metabarcoding based on high throughput sequencing was carried out using universal primer sets for cytochrome oxidase subunit I gene. Feces from 27 chicks collected in June and July in the period from 2016 to 2018 and intestinal contents from 33 adult and subadult cranes that were found dead almost throughout year in 2006–2013 in the field in eastern Hokkaido were used. Although compositions varied considerably in the cranes, both insects and fish were found in adults and subadults to the same extents, while insects were predominant in chicks. Both insects and fish were detected in all seasons for adults and subadults. Horse flies, scarab beetles and weevils accounted for the most of the insects regardless of the life stage. Dace, stickleback, flatfish and sculpin were the major fish species in adults, while chicks ate almost only stickleback. The results provide the first comprehensive data on carnivorous diets in wild red-crowned cranes in eastern Hokkaido as basis for conservation of red-crowned cranes, for which the life style and area continue to change.     

Nitrogen nutrition,leaf resistance,and leaf photosynthetic rate of the rice plant

The evidence that indicates a close association between nitrogen nutrition and the Photosynthetic rate of single rice leaves (Table 1) shows that the photosynthetic rate is related to the nitrogen content on a dry weight basis or on a leaf area basis, Photosynthesis of single leaves can be analyzed in terms of a series of diffusion resistances, i.e., stomatal, mesophyll, and carboxylation (1, 3, 6). Nitrogen nutrition may affect either one of these or more than two at the same time. Nitrogen nutrition affects mainly the mesophyll resistance, and the stomatal resistance to a lesser extent, in cotton, beans, and maize (10) while it affects both the stomatal and mesophyll resistance in sugar beet (8).     

Studies on the properties of organic matfer in buried humic horizon derived from volcanic ash

To investigate the relationship between the change of humus property and time factor, the humus composition in the buried humic horizons with the age from 28,000 years B.P. to the present was studied, according to the method presented by Kumada et al. (7).

The fH decreased with the elapse of time and in case of most of humus in the buried humic horizons with the age over 10,000 years, the fH became lower than 40 and were in the form of so-called ‘combined’ humus.

When 3,000-4,000 years have passed since the surface soil buried, the humic acid first moved . to ‘combined form.’ Second, after over 10,000 years, the fulvic acid moved to ‘combined form.’

The humification of ‘free’ humic acid proceeded with the elapse of time till around 5,000 years but of 'combined' humic acid till around 7,000 years. Both the humification-degree of ‘free’ humic acid after around 5,000 years and of ‘combined’ humic acid after around 7,000 years decreased. The humification-degree of ‘free’ and ‘combined’ humic acid from the samples with the age about 15,000 years B.P. to 28,000 years B.P. may be the same.     

Effect of nitrogen application during ripening period on photosynthesis and dry matter production and its impact on yield and yield components of semidwarf iniica rice varieties under water culture conditions

Abstract

A water culture pot experiment was conducted to analyze the effects of N application during the ripening period (RP) on photosynthesis, dry matter production, and its impact on grain ripening and yield in two semidwarf indica type varieties viz. Gui Zhao 2 (GZ) and BR3 (BR) compared with a japonica type variety Koganemasari (KO) under four N rates viz. 0 (N₀), 10 (N₁₀), 20 (N₂₀), and 40 (N₄₀) mg L^?1. Results showed that N application enabled to maintain a higher leaf area and delay leaf senescence in both indica and japonica type varieties but the decrease in the rate, of leaf area was higher in the former than in the latter and the rate was reduced with increasing N rates. Flag leaf photosynthesis and SPAD values of N treated plants were higher throughout the RP, showing the presence of a significant correlation either for each variety or all the varieties together. Higher photosynthetic rate was supported by higher leaf chlorophyll (SPAD value basis) content, stomatai conductance, and N concentration in leaf blades. Top dry matter content increased with increasing N rates mainly due to mean leaf area rather than NAR except for BR during RP but it was higher in KO than in GZ and BR. Reduction of shoot weight due to translocation of dry matter to panicles during RP was suppressed by N rates both in GZ and BR while shoot weight increased in the N-treated plants in KO. The dependency of KO on current photosynthates for panicle weight was found to be almost hundred percent while the contribution of stored carbohydrates in shoot before heading to panicle weight in GZ and BR was in the range of 4-27 and 33-54%, respectively and the rest was contributed by current photosynthates. The percentage increased with increasing N rates. Percentage of ripened grains (PRG) increased with increasing N rates in GZ and BR due to the increase in dry matter production and in the photosynthetic rates of apex leaves, despite the larger spikelet number and larger hull size. However, KO showed almost no variation although it had the highest PRG among the varieties. Brown rice yield followed the same pattern as that of PRG in GZ and BR and the highest yield was produced by BR followed by GZ and KO. These results suggest that N application during RP was more effective in increasing yield in the semidwarf indica type varieties than in the japonica type variety.