Estimation of light requirement for growth of <Emphasis Type="Italic">Zostera japonica</Emphasis> cultured seedlings based on photosynthetic properties

Photosynthesis and respiration rates were measured on 10 cm tall seedlings of Z. japonica at various temperatures and photosynthetic photon flux densities (PPFDs), and the daily compensation points in each season were estimated with a mathematical model based on photosynthetic properties and diurnal changes in solar irradiances. The seedlings were grown from seeds collected at Tategami-ura, Ago Bay, Mie Prefecture, Japan, and cultured for 1 week under the examined temperatures of 10–25°C. The estimated daily compensation points of Z. japonica ranged from 9.3 to 13.6% of the surface irradiance. The total PPFDs in daytime ranged from 3.8 to 5.3 mol photons m⁻² day⁻¹. The theoretical depth limits were calculated by the Beer-Lambert law concerning the relative light intensities of the sea surface and the extinction coefficient. The estimated lowest limit of Z. japonica agreed well with the lowest depth (7 m) previously reported. Therefore, the mathematical model in this study can be used to estimate the production and critical growing depth of Z. japonica. Differences in light requirements seem to be one of the reasons for the shallower habitats of Z. japonica in comparison with Z. marina.     

Fundamental studies on the hydrodynamic resistance of small pot traps

ABSTRACT:   The hydrodynamic resistance of small pot traps has been conducted in order to establish some basic information. The specific objectives of the study was to measure the hydrodynamic force and estimate the critical setting condition for traps. Five types of traps with different materials were used in the experiment: a netted semi-cylinder shape, a wire semi-cylinder shape, a heart shape, a box shape, and a cylinder shape. The hydrodynamic force of each trap was measured in a flume tank. Flow speeds in the flume tank were 0.1, 0.2, 0.3, 0.4, and 0.5 m/s. Attack angles for this study were 0, 15, 30, 45, 60, 75, and 90 degrees. At an attack angle of 0 degrees the main axis of the trap was parallel to the water flow and at 90 degrees it was vertical. The values of the hydrodynamic drag coefficient varied with traps: netted semi-cylinder shape, 2.75–5.96; wire semi-cylinder shape, 2.81–4.49; heart shape, 2.77–3.66; box shape, 2.39–2.97; and for cylinder shape, 3.57–3.67. The flow speed (0.5 m/s) was effective to set the netted semi-cylinder, wire semi-cylinder, box, and cylinder shaped traps. The same flow speed applied to the heart-shaped trap was only effective to a maximum of 30 degrees attack angles and below.     

High water temperature tolerance in photosynthetic activity of <Emphasis Type="Italic">Zostera japonica</Emphasis> Ascherson &; Graebner seedlings from Ago Bay,Mie Prefecture,central Japan

Photosynthetic activity of Zostera japonica seedlings was measured using a gas volumeter at 0 and 6 days in culture under eight light (0–800 μmol photons/m²/s) and ten water temperature conditions (5–35°C). Seedlings from Ago Bay, Mie Prefecture were cultured in incubators accurately controlled at each test temperature for 1 week. After 1 week, maximum gross photosynthesis (P _maxg) appeared at 29°C and most seedlings cultured at 30–35°C bleached and withered. At the same time, the light compensation point (I _c) increased only at 30°C during the culture period. As a result, the upper critical water temperature for survival was 29°C in Z. japonica seedlings, which agrees well with that for the southern boundary of Z. japonica around Japanese coast. It is necessary to monitor this species around this boundary as a bio-indicator for seawater warming.     

Central administration of neuropeptide B, but not prolactin-releasing peptide, stimulates cortisol secretion in sheep

Two neuropeptides, neuropeptide B (NPB) and prolactin-releasing peptide (PrRP), have been suggested to play important roles in control of the hypothalamic-pituitary-adrenal (HPA) axis in rodents. The aim of the present study was to clarify the central actions of NPB or PrRP in sheep. Ovariectomized ewes were surgically implanted with a cannula directed to the lateral ventricle. They received intracerebroventricular (icv) administration of 400 mul of artificial cerebrospinal fluid, NPB (0.05, 0.5 or 5 nmol), PrRP (0.5, 5 or 50 nmol) or corticotropin-releasing hormone (CRH, 0.5 or 5 nmol) through the cannula, and blood samples were taken 30 and 0 min prior to and 15, 30, 60 and 90 min after the injection. Cortisol concentrations in plasma were determined by enzyme immunoassay. Administration of 0.5 nmol NPB resulted in a significant increase in the cortisol concentration compared with the vehicle control, whereas the cortisol concentration after lower or higher doses of NPB did not differ from the control value. Thus, an icv injection of NPB produced a bell-shaped dose-response of cortisol concentration. Administration of PrRP had no significant effect on the cortisol concentrations at any dose examined. Icv injection of CRH dose-dependently increased plasma cortisol concentrations. These results demonstrate that central NPB stimulates cortisol secretion, suggesting that this neuropeptide plays some roles in control of the HPA axis in sheep. On the other hand, unlike its role in rodents, PrRP is unlikely to be involved in control of the HPA axis in this species.     

Lineage specific detection of the scaly form of the pen shell <Emphasis Type="Italic">Atrina</Emphasis> spp. by a loop-mediated isothermal amplification method

Taxonomy of the pen shell (genus Atrina) in East Asia has been confused because of the plasticity of the shell morphology and lack of unified morphological characteristics. We analyzed the mitochondrial cytochrome c oxidase subunit I (COI) sequence of the pen shell sampled from Ariake Bay and Seto Inland Sea, western Japan. All individuals were identified as the scaly form based on external morphology; however, their COI sequences were comprised of two distinct lineages. The sequence divergence between the two was 8.3%, indicating the high possibility that they are different species. The scaly form of the pen shell in Japan is one of the target species for resource enhancement, therefore COI lineage identification of broodstock individuals is critically important to avoid producing hybrid seed. We developed a loop-mediated isothermal amplification method that enables specific detection of the two lineages. This method can contribute to reducing the cost and time required for genotyping broodstock individuals prior to seed production.     

Effect of ensiling process of total mixed ration on fermentation profile,nutrient loss and in situ ruminal degradation characteristics of diet

This experiment aimed to determine the changes in chemical composition, fermentation profile, in situ disappearance characteristics, and nutrient losses of ensiled total mixed ration (TMR) containing steam‐flaked corn or brown rice (BR) during storage. TMRs for dairy cows, containing either steam‐flaked corn or BR at 31.9% with 15.2% rye silage, 40.5% alfalfa silage, 5.0% beet pulp and 7.0% soybean meal, were prepared (dry matter (DM) basis). Each TMR was placed in a plastic drum silo, stored at 23°C in an air‐conditioned room and sampled 0, 7, 14, 30, 90 and 210 days after preparation. In both grain sources, the fermentation products increased, while DM and starch storage losses increased and starch content greatly decreased during storage. The rapidly degradable fraction and effective ruminal degradability of DM, crude protein and starch increased during storage. These changes of dietary characteristics were large during 30 days of storage, but small after 90 days of storage. Replacing corn with BR led to increased fermentation products, starch loss and effective ruminal degradability of the ensiled TMR. These results indicate that the ensiling process of TMR changes the dietary characteristics and replacing corn with BR in TMR had a large impact on these dietary characteristics.     

A blinded randomized controlled trial evaluating the usefulness of a novel diet (aminoprotect care) in dogs with spontaneous food allergy

Aminoprotect Care (APC) is a novel diet composed of aminoacids, potato proteins and corn starch. The objectives of this study were to determine whether Maltese-Beagle atopic (MBA) dogs hypersensitive to corn exhibited clinical signs and changes in immunological markers after being fed APC. The study was designed as a blinded randomized controlled crossover experiment. Ten MBA dogs with signs of allergy within five days of ingesting corn were selected. Dogs were randomized to be fed either their maintenance diet with corn or APC for five days. After a washout of two weeks, diets were switched. Before and daily during each intervention, skin lesions were graded by an investigator while pruritus was assessed by another. Before and at the end of each intervention, the percentage of circulating CD4+CCR4+, corn-activated CD4+ T-lymphocytes and serum corn-specific IgE levels were measured and ratios of post:pre values calculated. During this trial, pruritus and skin lesions increased significantly in MBA dogs when ingesting corn while no such increase occurred when fed APC. Total, median and maximal pruritus values were significantly higher in MBA dogs ingesting corn compared to APC. There were no significant differences between interventions in the immunological parameters assessed. In summary, even though APC contains corn starch to which corn-sensitive MBA dogs often react, the ingestion of APC did not lead to significant increases in skin lesions or pruritus. Aminoprotect Care might prove valuable for management of food allergies. These experimental observations must be validated in large field studies.     

Burkholderia gladioli associated with symptoms of bacterial grain rot and leaf-sheath browning of rice plants

Rice plants with bacterial leaf-sheath browning and grain rot were observed in Fukuoka Prefecture in Japan during the autumn seasons of 1995 and 1996. Burkholderia spp. were consistently isolated from the infected leaf sheaths and grains. These isolates were pathogenic and induced symptoms of seedling rot, grain rot, and leaf-sheath browning in rice plants, as well as in some orchidaceous plants (cymbidium, dendrobium, and oncidium leaves), gladiolus leaves, and onion bulbs. On the basis of morphological, physiological and pathological tests, and species-specific polymerase chain reaction, the isolates were identified as belonging to either Burkholderia glumae or Burkholderia gladioli. B. gladioli, as well as B. glumae, attacked rice plants after artificial inoculation and reproduced the symptoms similar to those after natural infections. We confirmed that rice is an additional natural host of B. gladioli. It is clarified that bacterial grain rot of rice is caused not only by B. glumae but also by B. gladioli.     

IgE reactivity to vaccine components in dogs that developed immediate-type allergic reactions after vaccination

Allergic reactions after vaccination are considered as an important practical problem in dogs; however, their immunological mechanism has not been well understood. The present study was designed to investigate the relationship between IgE reactivity to the vaccines and immediate-type allergic reactions after vaccination in dogs. Sera from 10 dogs that developed immediate-type allergic reactions such as circulatory collapse, cyanosis, dyspnea, facial edema, and vomiting within 1h after vaccination with non-rabies monovalent or combined vaccines and sera from 50 dogs that did not develop allergic reactions after vaccination were collected. Serum IgE reactivity to the injected vaccines was measured by fluorometric ELISA using a mouse monoclonal anti-dog IgE antibody. Then, IgE reactivity to fetal calf serum (FCS) and stabilizer proteins (gelatin, casein, and peptone) included in the vaccines was measured in sera that had high levels of IgE to the vaccines. Levels of serum specific IgE to the vaccines in dogs with immediate-type allergic reactions (59-4173 fluorescence units [FU], mean +/- S.D.: 992.5 +/- 1181.9 FU) were significantly higher than those in control dogs (38-192 FU, 92.4 +/- 43.3 FU) (P < 0.001). Of the eight dogs that developed immediate-type allergic reactions and had high levels of serum specific IgE to the vaccines, seven had specific IgE directed to FCS. The IgE reactivity to the vaccines in sera from these dogs was almost completely inhibited by FCS. The other one dog had serum IgE directed to gelatin and casein included in the vaccine as stabilizers. The results obtained in this study suggest that immediate-type allergic reactions after vaccination in dogs were induced by type I hypersensitivity mediated by IgE directed to vaccine components. In addition, FCS, gelatin, and casein included in vaccines could be the causative allergens that induced immediate-type allergic reactions after vaccination in dogs.     

Mast cell tumor in the nasal cavity of a dog

An 11-year-old male Shetland sheepdog displayed epistaxis and nasal discharge from the left nasal foramen. Cytological examination of a smear sample obtained by rhinotomy revealed neoplastic mast cells in the nasal cavity, a definitive diagnostic sign of mast cell tumor. The case was treated by surgery combined with radiotherapy and chemotherapy. Eighteen days after the last treatment, marked enlargement of the mandibular lymph nodes and facial edema developed, and the dog was euthanized at the owner's request. At necropsy, metastatic proliferation of mast cells was confirmed in the lymph nodes and liver, but no neoplastic mast cells were observed in the nasal cavity.