Effects of a probiotic bacterial <Emphasis Type="Italic">Lactobacillus rhamnosus</Emphasis> dietary supplement on the crowding stress response of juvenile Nile tilapia <Emphasis Type="Italic">Oreochromis niloticus</Emphasis>

To test the effects of probiotic bacteria against crowding stress, juvenile Nile tilapia Oreochromis niloticus were fed commercial feed supplemented with 1 × 10¹⁰ cfu/g pellets of Lactobacillus rhamnosus for 3 weeks. The fish were confined and subjected to crowding for 7 and 14 days after which their physiological condition was investigated. The administration of probiotic prophylaxis improved growth performance even in the stressed fish. After 7 days of stress exposure, fish receiving probiotic-supplemented feed showed proactive behavior and coping responses to the stressor, as evidenced by elevated plasma glucose levels and osmolality, stabilized plasma electrolytes, and a higher RNA:DNA ratio. Fish stressed for 7 days and fed normal commercial diet showed impairment of plasma electrolytes; after 14 days, the plasma osmolality, electrolytes, glucose, and RNA:DNA ratio decreased, indicating physiological maladaptation to the stressor. The growth rate was also found to be reduced, suggesting that energy demand exceeded the energy available from metabolism and dietary uptake. This latter effect was not observed in fish fed the probiotic-supplemented diet. The results suggest that probiotic bacteria prophylaxis may increase energy availability for metabolic support of the crowding stress response and improve the stress coping capacity of fish.     

Characteristics of Collagen from Rohu (Labeo rohita) Skin

Acid soluble collagen (ASC) and pepsin soluble collagen (PSC) were isolated from rohu skin with the yield of 64.2 and 6.8% (dry weight basis), respectively. Both collagens had glycine as the major amino acid with imino acid content of 196–202 residues/1,000 residues and were characterized as type I collagen with molecular composition of (α1)₂α2-heterotrimer. Fourier transform infrared spectra of both collagens were similar, with no shift in wavenumber of all amide bands. The T_max value of ASC and PSC was 36.40 and 35.48°C, respectively. The zero surface net charge of ASC and PSC was found at pH 5.9 and 5.3, respectively.     

Characteristics and Functional Properties of Ovary from Squid Loligo Formosana

The characteristics and functional properties of the ovary from Loligo formosana were studied. Moisture (72.07 ± 0.24%) was dominant, followed by protein (18.64 ± 0.51%) and carbohydrate (7.44 ± 0.2%). Ash (1.39 ± 0.03%) and lipids (0.46 ± 0.5%) were found as the minor constituents. Albumin (79.02 ± 0.79%) was the major protein of the squid ovary, followed by glutelin-1 (8.31 ± 0.62%) and globulin (6.68 ± 0.08%). Nevertheless, prolamin and glutelin-2 constituted approximately 1% of the total proteins. Based on the electrophoretic studies, albumin had the largest band intensity. The squid ovary was rich in non-essential amino acids (52.26%) and high in hydrophobic amino acids (48.03%). It was also rich in polyunsaturated fatty acid (PUFA, 43.76 ± 0.84%), followed by saturated fatty acid (SFA, 39.36 ± 0.12%) and monounsaturated fatty acid (MUFA, 12.94 ± 0.55%). Ovary lipids had a high amount of docosahexaenoic acid (C22:6) (28.59%). At pH 3, the squid ovary powder (SOP) had the maximum solubility (96.39%), whereas the lowest solubility (38.33%) was observed at pH 9. The foaming capacity and stability of SOP were increased with increasing concentration up to 8% (p < 0.05). The globulin fraction showed the higher foaming capacity, as compared to albumin and glutelin-1 fractions. The squid ovary had good nutritional value and possessed excellent foaming properties. Therefore, the squid ovary could serve as a novel food additive or ingredient.     

Vitamin contents of eggs that produce larvae showing a high survival rate in the Japanese eel Anguilla japonica

This paper describes the relationship between the egg vitamin concentrations and the egg quality in the Japanese eel Anguilla japonica . No notable relation was found between any vitamin and the fertilization rate. Hatching and survival rates of larvae, however, significantly increased with an elevated level of egg vitamin C (VC). In contrast to VC, the relation between vitamins E (VE) and A (VA) concentrations and survival rate showed a clear peak, with a reduced survival rate at both higher and lower vitamin concentrations. The ratio of VE to lipid or highly unsaturated fatty acid (HUFA) in eggs positively correlated with hatching and survival rates of larvae. High-quality (HQ) eggs were determined as eggs that produced larvae having a survival rate higher than 80% at 8 days post hatch, and low-quality (LQ) eggs were determined as eggs that did not hatch. The level of VC of HQ was significantly higher than LQ. The results of this study suggest that HQ eggs, which produce larvae having a high survival rate, must have high levels of VC and VE/HUFA ratio and contain optimum levels of VA and VE in Japanese eel.     

Quality Characteristics of Waxy Hexaploid Wheat (Triticum aestivum L.): Properties of Starch Gelatinization and Retrogradation

The viscoelastic properties and molecular structure of the starch isolated from waxy (amylose-free) hexaploid wheat (WHW) (Triticum aestivum L.) were examined. WHW starch generally had lower gelatinization onset temperature, peak viscosity, and setback than the starch isolated from normal hexaploid wheat (NHW). Differential scanning calorimetry (DSC) showed that WHW starch had higher transition temperatures (T_o, T_p, and T_c) and enthalpy (ΔH) than NHW starch. However, when compared on the basis of amylopectin (AP) content, ΔH of WHW starch was almost statistically identical to that of its parental varieties. Typical A-type X-ray diffraction patterns were observed for the starches of WHW and its parental varieties. Somewhat higher crystallinity was indicated for WHW starch. WHW starch was also characterized by having greater retrogradation resistance. The high-performance size-exclusion chromatography (HPSEC) of amylopectin showed that each amylopectin yielded two fractions after debranching. Although WHW amylopectin had somewhat long B chains, little difference was observed in the ratio of Fr.III/ Fr.II between WHW and its parental varieties.     

Wireless monitoring of blood glucose levels in flatfish with a needle biosensor

A wireless biosensor system was developed for the continuous measurement of blood glucose levels in flatfish. The biosensor was implanted in the interstitial fluid under the scleral surface of the eyeball (EISF) to investigate the relationship between EISF and blood glucose levels. EISF glucose levels were found to be correlated with those in the blood and to be approximately the same as blood glucose levels in the range of 7–25 mg dl⁻¹. A needle-type biosensor was prepared for the continuous EISF glucose monitoring in flatfish. A working electrode was constructed using platinum iridium wire, and glucose oxidase was immobilized to the electrode. The biosensor was inserted into the EISF of flatfish for sensor implantation. A 650-mV potential (vs. Ag/AgCl) was applied by a wireless potentiostat to the working electrode for the amperometric glucose measurement. We investigated whether glucose in the EISF can be determined in vivo. The estimated glucose levels using a one-point calibration method were correlated with actual blood glucose levels. In conclusion, using a wireless biosensor system, we were able to monitor blood glucose levels in flatfish under free-swimming conditions for 16 h.     

Availability of potato protein concentrate as an alternative protein source to fish meal in greater amberjack (Seriola dumerili) diets

Potato protein concentrate (PPC) is a promising candidate as a fish meal (FM) substitute because it has high protein and essential amino acid content. In the present study, we replaced FM in greater amberjack diets with PPC to investigate the effect on growth and feed utilization. Four isonitrogenous, isolipidic and isocaloric experimental diets were prepared by substituting 0, 20, 40 and 60% of FM protein with PPC (Control, P20, P40 and P60 respectively). The in vitro protein digestibility of protein in PPC was 88.8%, relative to 100% protein in the FM. The in vitro protein digestibility of protein in the experimental diets also decreased with increasing PPC and was lowest at 84.2% in P60. After the 7‐week feeding trial, final body weight, weight gain and thermal growth coefficient tended to decrease with increasing PPC and were significantly lower in P60 than in the control (p < .05). Further, fish fed with diets P40 and P60 showed significantly lower feed conversion and protein efficiency ratios than the control group (p < .05). In conclusion, the results suggest that PPC can replace up to 20% of FM in the diet of greater amberjack without compromising the growth performance or feed efficiency.     

α-Melanocyte-stimulating hormone directly increases the plasma calcitonin level and involves calcium metabolism in goldfish

International Aquatic Research - The effects of α-melanocyte-stimulating hormone (α-MSH) on calcium metabolism were examined with goldfish. The scales on the left side of goldfish bodies...     

Divergent evolution of rice blast resistance <Emphasis Type="Italic">Pi54</Emphasis> locus in the genus <Emphasis Type="Italic">Oryza</Emphasis>

Background

The rice blast resistance gene Pi54 was cloned from Oryza sativa ssp. indica cv. Tetep, which conferred broad-spectrum resistance against Magnaporthe oryzae. Pi54 allelic variants have been identified in not only domesticates but also wild rice species, but the majority of japonica and some indica cultivars lost the function.

Results

We here found that Pi54 (Os11g0639100) and its homolog Os11g0640600 (named as #11) were closely located on a 25 kbp region in japonica cv. Sasanishiki compared to a 99 kbp region in japonica cv. Nipponbare. Sasanishiki lost at least six genes containing one other R-gene cluster (Os11g0639600, Os11g0640000, and Os11g0640300). Eight AA-genome species including five wild rice species were classified into either Nipponbare or Sasanishiki type. The BB-genome wild rice species O. punctata was Sasanishiki type. The FF-genome wild rice species O. brachyantha (the basal lineage of Oryza) was neither, because Pi54 was absent and the orientation of the R-gene cluster was reversed in comparison with Nipponbare-type species. The phylogenetic analysis showed that #11gene of O. brachyantha was on the root of both Pi54 and #11 alleles. All Nipponbare-type Pi54 alleles were specifically disrupted by 143 and 37/44?bp insertions compared to Tetep and Sasanishiki type. In addition, Pi54 of japonica cv. Sasanishiki lost nucleotide-binding site and leucine-rich repeat (NBS–LRR) domains owing to additional mutations.

Conclusions

These results suggest that Pi54 might be derived from a tandem duplication of the ancestor #11 gene in progenitor FF-genome species. Two divergent structures of Pi54 locus caused by a mobile unit containing the nearby R-gene cluster could be developed before domestication. This study provides a potential genetic resource of rice breeding for blast resistance in modern cultivars sustainability.

     

First report of ‘<Emphasis Type="Italic">Candidatus</Emphasis> Phytoplasma malaysianum’ associated with <Emphasis Type="Italic">Elaeocarpus</Emphasis> yellows of <Emphasis Type="Italic">Elaeocarpus zollingeri</Emphasis>

“Elaeocarpus yellows” (ELY) is a widely reported phytoplasma disease of Elaeocarpus zollingeri trees in Japan. The phytoplasma associated with ELY (ELY phytoplasma) had not been identified at the species level because its 16S rRNA sequence had yet to be reported. Here, we report the results of a sequence analysis based on 16S rRNA and secA gene sequences, which showed that the ELY phytoplasma is related to ‘Candidatus Phytoplasma malaysianum’. To our knowledge, this is the first report showing the occurrence of ‘Ca. P. malaysianum’ outside Malaysia and the infection of E. zollingeri by the phytoplasma.