Characterization of bacterial community composition in rotifer cultures under unexpected growth suppression

Unexpected growth suppression is common in rotifer mass culturing, and bacteria present in culture tanks are believed to be one of the main causes. We used a polymerase chain reaction (PCR)-amplified 16S ribosomal RNA (rRNA) gene finger-printing method to determine the bacterial community composition in water and that in association with rotifers present in tanks when rotifer growth was suppressed. Bacterial 16S rRNA genes representing Nautella sp. and Marinomonas sp. were identified as dominant in control tanks with good rotifer growth. In contrast, the bacterial community composition was more diverse at start-up in tanks where rotifer growth was suppressed. The community composition changed during rotifer cultivation, and bacterial sequences representative of Ruegeria sp. and Hyphomonas sp. were dominant when rotifer growth recovered. These findings indicate that the bacterial community composition varied according to the rotifer growth conditions and suggest that the initial microbial flora present in the culture water may cause rotifer growth suppression.     

Effects of dietary microalgal species and hormone treatment on the lorica size and reproductivity of heavy-ion beam irradiated rotifers

In aquatic seeding production, the feeding regime of fish larvae consists of rotifers to Artemia, while there is a lack of intermediate-sized feed in the range of 350–600 µm. To solve this problem, in our previous study, the euryhaline rotifer Brachionus plicatilis (L-type, Notojima strain) were irradiated with carbon heavy-ion-beams, and large-sized rotifer mutant lines (>?350 µm lorica length) were established. This study aimed to enhance the mutated morphometric characteristics and reproductivity through the combined use of three microalgal species (Nannochloropsis oculata, Tetraselmis tetrathele, and Chlorella vulgaris), and two hormones [juvenile hormone (JH) and gamma-aminobutyric acid (GABA)]. The combination of T. tetrathele and JH was effective in enhancing the mutated phenotype, and the largest lorica length of 344–425 µm was observed with no significant differences in population growth between the wild-type and mutant strains. The combination of N. oculata and GABA enhanced the population growth of the mutant line, and its growth rate was 2.4 times higher than that of the control group (without GABA). This study indicates that the morphometric characteristics and reproductivity of rotifer mutant lines could be regulated by feed and hormone supplementation. These findings can promote the efficient use of mutant rotifer lines in aquaculture facilities.

     

Phytotoxic activity of Chinese violet (Asystasia gangetica (L.) T. Anderson) and two phytotoxic substances

Chinese violet (Asystasia gangetica (L.) T. Anderson) is a perennial invasive weed belonging to Acanthaceae. Leaves of this weed have been suggested to possess phytotoxic activity. However, phytotoxic substances in this weed have not yet been reported. Therefore, the present study investigated phytotoxic activity of Chinese violet extracts and phytotoxic substances. The extracts of Chinese violet leaves inhibited the root and shoot growth of cress, lettuce, alfalfa, barnyard grass, ryegrass, and timothy, where the level of inhibition increased with increasing extract concentrations. Bioassay‐guided separations of the extracts led to isolation of two phytotoxic substances, indole‐3‐carboxaldehyde and (6R,9S)‐3‐oxo‐α‐ionol. Indole‐3‐carboxaldehyde significantly inhibited the root and shoot growth of cress at concentrations ≥100 and 30 μmol L^?1, respectively, and concentrations of the substance required for 50% growth inhibition were 210 and 127 μmol L^?1 for cress roots and shoots, respectively. The other substance, (6R,9S)‐3‐oxo‐α‐ionol, was reported to have strongly inhibited cress roots and shoots. The present results suggest that Chinese violet contains two phytotoxic substances indole‐3‐carboxaldehyde and (6R,9S)‐3‐oxo‐α‐ionol, and those substances may play an important role in the phytotoxic activity of Chinese violet.     

A case of nontraumatic gas gangrene in a common marmoset (Callithrix jacchus)

The common marmoset is widely used in neuroscience and regenerative medicine research. However, information concerning common marmoset disorders, particularly infectious diseases, is scarce. Here, we report a case of a female common marmoset that died suddenly due to gas gangrene. The animal presented with gaseous abdominal distention at postmortem, and Clostridium perfringens type A was isolated from several tissues. Vacuoles, a Gram-positive bacteremia and intravascular hemolysis were observed microscopically in the muscles, liver and lungs. On the basis of these findings, we diagnosed nontraumatic gas gangrene caused by Clostridium perfringens type A in this common marmoset.     

Bark stripping by sika deer on veitch fir related to stand age, bark nutrition, and season in northern Mount Fuji district, central Japan

We carried out this study to clarify the relationships between the seasonal changes of bark stripping and food quality, and between bark-stripping intensity and bark nutrition with age of veitch fir (Abies veitchii) by sika deer (Cervus nippon) in the northern Mount Fuji district, from June 2000 to July 2003. We found that sika deer gnawed and ate all of the bark stripped, and a seasonal change in bark stripping occurred from December to May or June with a peak in March–April. The stripping period largely overlapped with the periods of low food availability and poor food nutrition (indicated by fecal chemical component index) of sika deer, from January to April. Both bark nutritional quality and bark-stripping intensity related to stand age and tree size of veitch fir negatively. Consequently, bark-stripping intensity related to bark nutritional quality positively. February is the worst forage period in terms of both quantity (due to deep snow) and quality (indicated by fecal chemical components). There was a time lag of 1 to 2 months in the peak of bark stripping in March–April when compared with the poor forage period in February. This time lag may suggest that sika deer need more nutritious and easily digested food from March due to increased nutrient demands that result from depleted body condition in both sexes, gestation of pregnant females, and the recovery of active metabolism.     

Shear tests of double shear plate connector joints in sugi—Japanese larch composite glulam beams

To study the shear strength of structural joints in sugi (Cryptomeria japonica D. Don) — Japanese larch (Larix kaempferi Carriere) composite glulam beams using structural connectors with double shear plates, shear tests were conducted on two types of joint (post-beam and girder-beam). Two types of the composite beam (240 and 300 mm depth) were prepared for the tests. Ordinary sugi glulam beam and Japanese larch glulam beam were also used as control specimens. The load—displacement curves of joints in composite beams were somewhere between those of sugi and Japanese larch glulam beams. The shear strength of joints in composite beams was higher than that in the sugi glulam beam control. However, the allowable loads of the joints in composite beams were lower than those in the sugi beam with 240 mm depth. Large variation of maximum load of the joints in the composite beams resulted in lower allowable load.     

Development of green onion and cabbage certified reference materials for quantification of organophosphorus and pyrethroid pesticides

Green onion and cabbage certified reference materials for the analysis of pesticide residues were issued by the National Metrology Institute of Japan, part of the National Institute of Advanced Industrial Science and Technology. Green onion and cabbage samples were grown so as to contain several kinds of organophosphorus and pyrethroid pesticides, and those were collected from a field in the Kochi Prefecture in Japan. The certification was carried out by using multiple analytical methods to ensure the reliability of analytical results; the values of target pesticides (diazinon, fenitrothion, cypermethrin, etofenprox, and permethrin for green onion and chlorpyrifos, fenitrothion, and permethrin for cabbage) were obtained by isotope dilution mass spectrometry. Certified values of target pesticides were 0.96-13.9 and 2.41-6.9 mg/kg for green onion and cabbage, respectively. These are the first green onion and cabbage powder certified reference materials in which organophosphorus and pyrethroid pesticides are determined.     

Acute myelomonocytic leukemia (AML-M4) in a dog with the extradural lesion

A two-year-old dog having presented with neurological signs showed marked leukocytosis and appearance of blast cells in the peripheral blood. Hematological and bone marrow examination showed an increase in blasts having both myeloid and monocytic cells characteristics. The dog was diagnosed with acute myelomonocytic leukemia (AML-M4) on the basis of bone marrow findings. Although the dog was treated with a multi-combination chemotherapy, the neurological abnormalities progressed and the dog was euthanized. Myelographic examination and necropsy revealed the extradural lesion formed by AML-M4 around the cervical spinal cord and this lesion was considered as a cause of the neurological signs.     

Inclusion body hepatitis caused by fowl adenovirus in broiler chickens in Japan, 2009-2010

From January 2009 to June 2010, many broiler chicks suddenly died without clinical signs. The mortality rates were from 1.2% to 17.0% in affected flocks. Inclusion body hepatitis (IBH) was detected in 13 prefectures (northern, eastern, western, and southern areas) in Japan. The livers were enlarged and pale. The bursa of Fabricius and thymus had not atrophied. Multifocal necroses of hepatocytes with basophilic intranuclear inclusions were seen in the liver. Eosinophilic intranuclear inclusion bodies in hepatocytes were rare. Focal necrosis of acinar cells with basophilic intranuclear inclusions was found in the pancreas. Basophilic intranuclear inclusion bodies were detected in intact surface epithelial cells of gizzard and epithelial cells of the small intestine. The intranuclear inclusions of liver, pancreas, gizzard, and small intestine were stained positively for immunohistochemistry of fowl adenovirus (FAV) antigen. Ultrastructurally, basophilic intranuclear inclusions consisted of viral particles approximately 70 nm in diameter and arranged in a crystalline array. FAV was isolated from the liver of chickens affected with IBH. The serotype of most isolates was 2. This study suggests that IBH produced by FAV is epidemic in broiler chicks in Japan and that the present cases occurred as the primary disease without the association of infectious bursal disease virus or chicken anemia virus.