Gut bacterial community profile in Pacific white shrimp Litopenaeus vannamei following 5‐aminolevulinic acid supplementation

Changes in the diet have been previously reported to alter the gut bacterial profile in several organisms, including shrimp. These shifts in microbial structure either promote beneficial effects to the host or cause diseases. Supplementation of 5‐aminolevulinic acid (5‐ALA), the precursor of tetrapyrroles, has been previously reported to enhance shrimp's immune response. To know whether 5‐ALA has effects on the gut bacterial structure in Pacific white shrimp (Litopenaeus vannamei), we investigated the bacterial communities in the intestine and stomach of L. vannamei using high‐throughput Illumina sequencing of 16S rRNA gene libraries. One week of 5‐ALA supplementation altered the bacterial community structure (beta diversity) in both tissues, as shown by the results of multi‐dimensional scaling (MDS) plots and analysis of similarities (ANOSIM). DESeq2 analysis revealed enrichment of differentially abundant taxa in the 5‐ALA group (e.g. Enhydrobacter and Oceaniovalibus) and control group (e.g. Tenacibaculum and Mycobacterium). Metagenomic predictions suggested that the control group had more KEGG pathways associated with ‘metabolism’ than the 5‐ALA group. This study suggests that 5‐ALA supplementation potentially promotes the formation of a beneficial bacterial community structure in shrimp. This is the first report on the effect of 5‐ALA supplementation on the bacterial community profile in any organism.     

Mechanism of self-sterility in a hermaphroditic chordate

Hermaphroditic organisms avoid inbreeding by a system of self-incompatibility (SI). A primitive chordate (ascidian) Ciona intestinalis is an example of such an organism, but the molecular mechanism underlying its SI system is not known. Here, we show that the SI system is governed by two gene loci that act cooperatively. Each locus contains a tightly linked pair of polycystin 1-related receptor (s-Themis) and fibrinogen-like ligand (v-Themis) genes, the latter of which is located in the first intron of s-Themis but transcribed in the opposite direction. These genes may encode male- and female-side self-recognition molecules. The SI system of C. intestinalis has a similar framework to that of flowering plants but utilizing different molecules.     

Flower and seed production in a series of flowerings from sporadic events before to after mass flowering of the dwarf bamboo Sasa veitchii var. hirsuta

The aim of this study was to determine seed production patterns in a series of flowerings from sporadic events before to after mass flowering and to clarify the relationship between the occurrence of second flowering and seed production in the first flowering of mass-flowering events for S. veitchii var. hirsuta. The results revealed that ratios of numbers of seeds to florets per inflorescence in the first and second flowerings of a mass-flowering event were as large as those in the first flowering of a sporadic-flowering event before mass flowering, and were larger than those in the second flowering of a sporadic-flowering event before mass flowering and in both flowerings of a sporadic-flowering event after mass flowering. However, estimated number of produced seeds per square meter in mass flowering was higher than that in sporadic flowering before it. This suggests that seed production is promoted in mass flowering, and that sporadic flowering beforehand can potentially contribute to successful regeneration. At a site where seeds were produced in the first flowering of a mass-flowering event, flower production and the seed germination ratio were smaller in the second flowering. Conversely, at a site where few seeds were produced in the first flowering of a mass-flowering event, there was no significant difference in flower production between the first and second flowerings, and the seed germination ratio in the second flowering was more than 40 %. This suggests that the second flowering of a mass-flowering event is related to seed production in the first flowering.     

Utilization of genetically modified soybean meal in Nile tilapia <Emphasis Type="Italic">Oreochromis niloticus</Emphasis> diets

The utilization of genetically modified soybean meal (GM SBM) was compared with that of non-GM SBM in Nile tilapia. Four experimental diets were formulated to include either non-GM or GM SBM at 34 or 48%, respectively. These diets were fed to juvenile Nile tilapia (49.5 g average weight) for 12 weeks. The uptake of the cauliflower mosaic virus 35S promoter fragment of the GM SBM in fish muscle was examined at 8th and 12th week. After 12th week, fish were fed the non-GM SBM diets to determine the residual span of the incorporated promoter fragment. There was no significant difference in specific growth rate or feed efficiency between GM and non-GM groups at the same inclusion level. A small number of muscles from fish receiving both levels of GM SBM diet were positive for the promoter fragment. Additionally, the promoter fragment was not detected by the second day after changing to the non-GM SBM diets. These results indicate that the utilization of GM SBM was similar to that of non-GM SBM and the promoter fragment was rarely found in fish muscles, suggesting that suitability and safety of GM SBM in Nile tilapia diet were similar to those of non-GM SBM.     

Species-specific polymerase chain reaction primers for Lactococcus garvieae

A dihydropteroate synthase gene from the chromosomal DNA of the fish-pathogenic bacteria Lactococcus garvieae (formerly Enterococcus seriolicida ) was cloned. This gene was then chosen as the target for polymerase chain reaction (PCR). The designated PCR primer set only amplified a 709-bp DNA fragment from L. garvieae strains, and did not amplify the same molecular size fragment from related species of L. lactis, Enterococcus faecalis, E. faecium or β-haemolytic Streptococcus sp. The kidney tissue of yellowtail, Seriola quinqueradiata (Temminck and Schlegel), a species which is naturally infected with L. garvieae , and also kidney tissue samples of healthy yellowtail were stored in TNES-Urea. The DNA was extracted from tissue samples by a modification of the standard method and by a boiled-extraction method. In particular, template DNA was utilized within 30 min following extraction and purification by the boiled-extraction method. These species-specific PCR primers could amplify a L. garvieae target sequence from yellowtail which were naturally infected with L. garvieae . The total procedure for the diagnosis of L. garvieae infections in fish, from the point of DNA extraction to observation in an agarose gel following electrophoresis, can be performed in less than 4 h.     

cDNA microarray analysis of interleukin-1β-induced Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis> kidney cells

ABSTRACT:   Interleukin-1β (IL-1β) cDNA of Japanese flounder was found to consist of 1329 bp, encoded 247 amino acid residues. Among the fish IL-1β in the databases, the one with the highest identity of Japanese flounder IL-1β was that of seabass (62% identity). The expression of IL-1β was induced by treatment with concanavalin A (ConA)/phorbol myristate acetate (PMA) and lipopolysaccharide. The copy number of IL-1β mRNA was increased 30-fold after stimulation with ConA/PMA. Of 871 cDNA on a microarray, 93 genes (10.7%) were up-regulated or down-regulated by IL-1β at 1, 3 and 7 days post-injection. The induced gene expression was highest on day 1 followed by day 3 and day 7. A total of 7% of known and 3.7% of unknown genes of the 871 tested genes were differentially expressed. Of the genes tested, 7.4% were up-regulated and 3.3% were down-regulated. Cytokine genes such as tumor necrosis factor, granulocyte colony stimulating factor and chemokine receptor A were induced in response to IL-1β. Cell surface antigens such as IgM, MHC class I and CD20 receptor were up-regulated. Signal transduction genes such as Toll-like receptor 1 and SH3P2 were also up-regulated. The glucocorticoid receptor and cAMP early repressor were down-regulated in our microarray analysis.     

Isolation and molecular characterization of hemocyte sub-populations in kuruma shrimp Marsupenaeus japonicus

Fisheries Science - Crustacean hemocytes, which have usually been classified morphologically based on methods using Giemsa or May-Giemsa stains, have recently been categorized using monoclonal...     

Effects of moisture in wood materials on the SNR of GPS signals

This study was performed to investigate the factors responsible for the reduction in the signal-to-noise ratio (SNR) of a global positioning system (GPS) when used in a forest. We investigated the relationship between the SNR values of GPS signals and the moisture in wood materials and clarified this relationship through experimentation and simulation. Although the wood material itself had a minimal effect on SNR reduction, moisture in the wood had an obvious effect. It is noteworthy that wood material with a moisture resistance quantity (Mw) of 2 g/cm² caused a reduction of more than ~10 dB in the SNR. This Mw value corresponds to Japanese cedar with a green stem thickness of ~7 cm. Under unobstructed sky conditions, SNR is less than ~20 dB, so a reduction of 10 dB has a marked effect on GPS reception. The reduced SNR under canopies resulted from moisture in stems and the canopy. Furthermore, a simulation performed in a Japanese cedar forest revealed that 77.8% of the SNR reduction was caused by stems, 8.1% by branches, and 14.1% by needles.     

Effects of arginine supplementation on growth performance and plasma arginine,ornithine and citrulline dynamics of rainbow trout,Oncorhynchus mykiss

This study aimed to re‐evaluate the effect of excessive arginine supplementation on growth and feed efficiency of rainbow trout, and to assess the effect of dietary arginine supplementation on hepatic amino acid composition, expression of arginase Ⅱ (ARG 2), inducible nitric oxide synthase (iNOS), and heat shock protein 70 (HSP70) genes in the intestine, and plasma arginine, ornithine, citrulline and urea levels at 0, 6, 12 and 18 hr‐postprandial. Rainbow trout (body weight: 60.5–65 g) were fed diets containing 1.47 (control [CTRL]), 3.89 (3.89A) and 5.64% (5.64A) arginine for nine weeks. Higher muscle protein content was observed in 3.89A than CTRL (p < 0.05). In postprandial study, plasma arginine of 5.64A kept increased until 12 hr‐postprandial and reached identical value (around 150 µg/ml) until 18 hr‐postprandial in 5.64A. Significant increase of plasma arginine level was only observed in arginine supplemented group. Meanwhile, plasma citrulline level in CTRL was significantly higher than in 5.64A at 18 hr‐postprandial. A significantly higher hepatic citrulline level was also observed in CTRL than in 5.64A (p < 0.05). Significantly higher plasma and hepatic free ornithine level was observed in 5.64A than CTRL while significantly higher expression of intestinal ARG2 and HSP70 was found in arginine supplemented groups. These results suggest that citrulline availability seems to be stimulated by arginine deficiency in the CTRL and the presence of arginase in the intestine to regulate excess dietary arginine.