Adverse effects of low concentrations of dietary RNA addition on the growth,food intake and kidney weight of young chickens

1. The effects of 0, 10 and 50 g/kg of RNA in diets on the growth and food intake of chicks from 6 to 21 d of age were examined. Their effects on renal tissue were examined by light microscopy at the end of experiment.

2. Total food intake and growth decreased with the increase in dietary RNA content and kidney weight was significandy increased by 50 g/kg RNA addition. A significant increase in liver weight was also observed in chickens fed on the diet‐supplemented with 10 g RNA/kg.

3. The enlarged kidney caused by dietary RNA contained many crystals which were composed mainly of calcium salts but did not contain purines.

4. It is concluded that relatively low dietary RNA concentrations decrease food intake and growth and cause enlarged kidneys which contains many crystals composed mainly of calcium salts.     

Kinetic constants for the inhibition of acetylcholinesterase by phenyl carbamates

The kinetic constants of a variety of substituted phenyl N-methyl- and N,N-dimethylcarbamates, which inhibit bovine erythrocyte acetylcholinesterase, were determined by various experimental procedures. A procedure in the presence of a chromogenic substrate was developed, based on the suggestion of Hart and O'Brien, and was compared with the conventional Main method. The dissociation equilibrium constant, K_d, and the carbamylation rate constant, k₂, were shown to apparently depend on the inhibitor concentration range used for the determination in both procedures. Assuming that the binding of further inhibitor molecules to the reversible complex and the carbamylated enzyme is significant under conditions with high inhibitor concentrations, the concentration dependence of the kinetic constants was nicely delineated. It is indicated that reliable constants are obtainable with a rather low inhibitor concentration range, whose product by k_i is of the order of 0.2–1.0 min^?1.     

Prototheca zopfii genotypes isolated from cow barns and bovine mastitis in Japan

This study is the first investigation on Japanese isolates of Prototheca zopfii from bovine mastitis and the cow-barn surroundings by molecular characterization to clarify routes of infection for bovine protothecal mastitis. We performed isolation of Prototheca from cow-barn surroundings (drinking water, sewage and feces) and milk samples from cases of bovine mastitis. Genotypes of the 32 isolates of P. zopfii from cow-barn surroundings and 67 isolates from mastitis were analyzed by genotype-specific PCR assays and restriction fragment length polymorphism (RFLP) assays. All mastitis isolates were identified as P. zopfii genotype 2. Conversely, 29 isolates from cow-barn surroundings were identified as P. zopfii genotypes 1 and 3 isolates as genotype 2, respectively. Given these results, both genotypes of P. zopfii could exist in cow-barn surroundings, but no sites were identified as frequent sources of P. zopfii genotype 2. P. zopfii isolates should thus be further explored with regard to genotype to clarify the reservoir of etiological agents in bovine Prototheca mastitis.     

Basin-scale distribution pattern and biomass estimation of Japanese anchovy Engraulis japonicus in the western North Pacific

The distribution pattern and biomass of the Japanese anchovy Engraulis japonicus in the offshore region of the western North Pacific (north of 35°N and west of 170°E) were studied using a quantitative echosounder. This is the first attempt at such a study in this region. Data were collected in summer from 2004 to 2007. The biomass was estimated using data collected at 38?kHz. Species compositions in the backscatterings from pelagic fish were assigned based on the results of trawl hauls taking account of sea surface temperature (SST). Japanese anchovy tended to be high density to the west of 153°E and were distributed in an SST range of 9?C24?°C. Although the temporal and spatial coverage of the survey differed each year, at least 1.5?C3.4 million tons of Japanese anchovy were present in the survey area between 2004 and 2007. To take account of the spatial coverage of the survey each year, the most reliable biomass estimate for this region in the time period was 3.4 million tons (coefficient of variation?0.22).     

Comparative study on extractive components of fresh and boiled gonads of three species of sea urchins from the Gulf of Thailand

Proximate compositions and extractive components of the gonads (roes) of three species of sea urchins, namely, Diadema setosum, Salmacis sphaeroides and Toxopneustes pileolus, from the Gulf of Thailand were identified and the boiling effect on these extractive components of these sea urchin roes studied. Of the three species tested, the gonads of D. setosum had the lowest moisture (62 %) and ash (2 %) contents and the highest protein (15 %) and lipid (11 %) contents. Major extractive constituents of the roes of D. setosum were taurine, arginine, lysine, glycine, tyrosine, valine, leucine, isoleucine, alanine, glutamic acid and inosine 5′-monophosphate; those for the roes of S. sphaeroides were glycine, lysine, alanine, arginine, ATP and adenosine 5′-diphosphate; those for the roes of T. pileolus were glycine, alanine, serine, ATP and adenosine 5′-monophosphate, respectively. Boiling in 3 % brine (98–100 °C, 2 min) drastically reduced the amounts of both free amino acids and ATP-related compounds of sea urchins belonging to all these species.     

Control of dissolved oxygen levels of water in net pens for fish farming by a microscopic bubble generating system

ABSTRACT:   A microscopic bubble generating system (MBGS) has been developed to control dissolved oxygen (DO) levels suitable for fish farming. The MBGS has been tested to confirm its capability in net pens. Water conditions in a fish farm were monitored every two hours from June to October 2004 by setting an online vertical profiling system (OVPS) close to the net pen. DO in the net pen water decreased to physiologically stressful levels for the fish during the night (4.84–5.51 mg/L), while the DO was kept in saturated conditions during the day, due to oxygen supply from phytoplankton. The MBGS was operated from the evening to the morning of the next day for 16 h, to successfully create DO-saturated conditions in the net pen water at night. By using microscopic bubbles during the warm seasons, DO levels in the net pen water could be improved to a level suitable for fish farming. However, the low DO levels (<5.0 mg/L) of the bottom water occasionally extended to the net pen layers, despite the supply of microscopic bubbles to the water. To maintain the DO of the net pen water at levels suitable for fish farming, DO supply to the net pen water and the bottom water needs to be increased, and the organically enriched sediment just below the net pens needs to be treated.     

Predation dynamics of mackerel on larval and juvenile anchovy: is capture success linked to prey condition?

We tested whether the predation dynamics of chub mackerel Scomber japonicus and spotted mackerel S. australasicus on young anchovy Engraulis japonicus relates to individual growth characteristics of the prey and could account for the growth-selective survival predicted by recruitment hypotheses. Juvenile and adult mackerel were sampled along with their young anchovy prey field in 2004 (juvenile mackerel and larval anchovy) and 2005 (adult mackerel and juvenile anchovy) off the Pacific coast of Honshu, Japan. The recent 5-day mean growth rate of larval and juvenile survivors and prey found in the stomach of mackerel was estimated from the otolith microstructure. No significant difference was found between the recent growth of larval or juvenile survivors and that of preyed individuals. We conclude that despite a relatively small body size, the high activity level and predation skills displayed by mackerel prevent fast-growing larvae and early juveniles from benefitting in terms of the expected survival advantage over slow-growers. Hence, growth-selective predation mortality of larval fish would depend on the feeding ecology of the predator rather than predator size. Selection for fast growth is more likely to occur under predation pressure from invertebrate organisms and small pelagic fish specialized on zooplankton, such as herring and anchovy.     

Mineral composition of leaves and bark in aluminum accumulators in a tropical rain forest in Indonesia

Mineral composition including AI, Ca, Mg, P, S, and Si and relationships between Al and other elements such as Ca, Mg, P, S, and Si in leaves and bark of trees in a tropical rain forest in West Sumatra were studied. Sixty five tree species and 12 unidentified trees were referred to as AI accumulators based on Chenery\s's definition (more than 1 g kg^-1 Al in leaves). For most of the Al accumulators, Al concentration in leaves was higher than in bark. However, some members of Euphorbiaceae, Melastomataceae, and Ulmaceae families showed a reverse trend. Most of the non-accumulators also showed a higher Al concentration in bark than in leaves. These results indicated that there was a difference in the mechanism of Al accumulation in tree bodies. Some of the Al accumulators showed an extremely high Al concentration (more than 10 g kg^-1) not only in the mature leaves, but also in the new leaves. Analysis of the relationships between the concentration of Al and the other 5 elements in leaves, revealed that Al accumulators could be separated into two groups at the Al concentration of 3 g kg^-1. This finding suggested that new criteria based on Al concentration (23 g kg^-1) or Al/Ca ratio in leaves could be proposed in order to define Al accumulators, apart from Chenery's criterion. Aluminium accumulators with an Al concentration in leaves lower than 3 g kg^-1 (AI accumulators <3 g kg^-1) showed the same trend as the non-accumulators in terms of these elemental relationships, while Al accumulators with an Al concentration in leaves higher than 3 g kg^-1 (AI accumulators 23 g kg^-1) showed a different trend from the non-accumulators. The Al accumulators 23 g kg^-1 and the other trees (AI accumulators < 3 g kg^-1 and non-accumulators) showed separately positive correlations between the concentrations of AI and Ca (or Mg) in the leaves. This observation seems to be opposite to general findings in plant nutrition, i.e. inhibition of Ca or Mg uptake by AI. A positive correlation between Al and S was also observed for all the trees. The Al accumulators ≥3 g kg^-1 showed positive correlations between the concentrations of Al and P (or Si) in the leaves, unlike the other trees. These findings suggested that Al stimulated P, S, or Si accumulation in leaves or Al was transported with P, S, or Si for the Al accumulators ≥3 g kg^-1. No negative relationships between Al and the other 5 elements in the leaves were observed for the Al accumulators ≥3 g kg^-1.     

Migratory waterfowl as flying reservoirs of Yersinia species

Intestinal contents of tufted ducks and faecal samples from two other species of migratory birds were examined for Yersinia species of organisms. From 296 tufted ducks Yersinia species were isolated from 10 (3.4 per cent), from 223 swans Yersinia species were recovered from eight (3.6 per cent) but none were recovered from the faeces of 121 pintail ducks. Since the isolates differed from each other in their biochemical characteristics and, or, O serotypes, yersinia infection in these migratory waterfowl seemed to be sporadic.