Net depth response of a depth-controllable (towed) gillnet for fish sampling

SUMMARY: Flume-tank experiments were performed to examine the depth response of a new type of depth-controlled gillnet. Variations of net depth were investigated as the warp was paid out and wound up for different changes of warp length, main sinker weights, and winch speeds. In most experiments, when the warp finished paying out, the net continued to descend and then ascended slightly to an equilibrium depth (overshoot phenomenon). The overshoot distance was nearly constant when the warp was wound up and increased linearly with increasing winch speed when the warp was paid out. An increase in winch speed reduced net settling time, which converged on a constant value for both paying out and winding up.     

Powdery Mildew of Prairie Gentian: Characteristics,Molecular Phylogeny and Pathogenicity

In March 1999, we found prairie gentian (Eustoma grandiflorum) infected with powdery mildew in a greenhouse in Oita Prefecture, Japan. Morphological observation revealed that the causal fungus belongs to the mitosporic genus Oidium subgenus Pseudoidium [teleomorph: Erysiphe sensu Braun and Takamatsu (2000)]. Precise taxonomic position of the fungus, however, is uncertain due to lack of the perfect stage. We determined the nucleotide sequence of the rDNA ITS region of the fungus. Comparison of the sequence with those obtained from DNA databases of this fungal group revealed that the sequence is identical to those of powdery mildews from garden four-o'clock (Mirabilis jalapa) and broad bean (Vicia faba). Inoculation of an isolate from garden four-o'clock caused mildew on prairie gentian and broad bean, suggesting that the prairie gentian mildew originates from garden four-o'clock or broad bean. Molecular phylogenetic analysis indicated a close relationship of this fungus to Erysiphe baeumleri on Vicia spp. and E. trifolii on Trifolium pratense. From these results, we propose that prairie gentian mildew diverged from a Fabaceae-parasitic ancestor. Received 14 March 2002/ Accepted in revised form 28 May 2002     

Auxins increase the occurrence of leaf-colour variants in Caladium regenerated from leaf explants

Leaf explants of Caladium ‘Pink Cloud’ were cultured in vitro on MS medium containing various auxins (NAA, IBA, IAA, 2,4,5-T and 2,4-D) in combination with cytokinin (BA). NAA gave the most vigorous in vitro propagation of this plant, and only 15% of the plants were leaf-colour variants on the medium containing 0.5 μmol NAA. Leaf colour variation was observed in all plants regenerated on the medium containing 2,4-D at 0.5–4.5 μmol. In hormone-free medium, only a few leaf-colour variants (6%) occurred, but the rate of plant regeneration was very low. Application of 0.5 μmol NAA together with 4.5 μmol BA seemed to be the most appropriate for in vitro propagation of Caladium ‘Pink Cloud’ with only a few leaf-colour variants.     

Simultaneous detection of multiple mycotoxins in broiler feeds using a liquid chromatography tandem-mass spectrometry

Mycotoxins are secondary fungal metabolites that are typically present in grain and feed ingredients used for animal feeds. An analytical method using LC-ESI-MS/MS was developed to quantify nine mycotoxins, consisting of aflatoxin B₁ (AFB₁), AFB₂, AFG₁, AFG₂, T-2 toxin, deoxynivalenol (DON), nivalenol (NIV), zearalenone (ZEA) and ochratoxin A (OTA) in broiler feeds. In total, 100 samples of broiler feeds were collected from poultry farms in Central Thailand. The survey found that AFB₁ and ZEA were the most prevalent mycotoxins in the feed samples at percentages of 93% and 63%, respectively. The limit of detections (LODs) of investigated mycotoxins was 0.20–0.78 ng/g. AFB₂, DON, AFG₁, NIV and T-2 toxin were also detectable at low contamination levels with percentages of 20%, 9%, 7%, 5% and 1%, respectively, whereas OTA and AFG₂ were not detected in any of the feed samples. These results suggest that there is a very low level of risk of the exposure to mycotoxins in feeds obtained from broiler farms in Central Thailand.     

Involvement of microaerophilic iron-oxidizing bacteria in the iron-oxidizing process at the surface layer of flooded paddy field soil

Journal of Soils and Sediments - To reveal whether microaerophilic Fe(II)-oxidizing bacteria (FeOB) participate in the Fe(II) oxidation at the oxic-anoxic interface in flooded paddy field soil,...     

Enhancement of antigen-specific immunoglobulin G production in mice by co-administration of L-cystine and L-theanine

Supplementation with both cystine and glutamic acid increases the synthesis of glutathione (GSH), which has a marked effect on immune cell function, as compared with supplementation with either amino acid alone in human macrophages in vitro. As dietary glutamic acid is metabolized during intestinal transport, oral administration of L-theanine (gamma-glutamylethylamide), which is metabolized to glutamic acid mainly in the liver, may act as a glutamic acid donor in vivo. The present study was performed to investigate the effects of oral administration of L-cystine and/or L-theanine on GSH levels and immune responses. Co-administration of L-cystine (200 mg/kg) and L-theanine (80 mg/kg) for 11 days before immunization significantly increased the levels of total GSH in the liver 6 hr after immunization as compared with the levels in control mice. To examine the effects of administration of L-cystine and/or L-theanine on the balance of T helper (Th) 1/Th2 cell responses, the serum ratios of the Th1 cytokine, interferon (IFN)-gamma, and the Th2 cytokine, interleukin IL-10, were investigated. At 24 hr after immunization, co-administration significantly increased the IL-10/IFN-gamma ratio compared with the ratios of the control and single-administration mice. Furthermore, co-administration before primary immunization significantly enhanced serum antigen-specific IgG levels. Taken together, these findings suggest that co-administration of L-cystine and L-theanine enhances antigen-specific IgG production partly through augmentation of GSH levels and Th2-mediated responses.     

Telomere length and telomerase activity in canine mammary gland tumors

OBJECTIVE: To measure telomere length and telomerase activity in naturally occurring canine mammary gland tumors. SAMPLE POPULATION: 27 mammary gland tumor specimens obtained during resection or necropsy and 12 mammary gland tissue specimens obtained from healthy (control) dogs. PROCEDURE: Telomere length in tissue specimens was measured by use of restriction endonuclease digestion and Southern blot analysis. Telomerase activity was measured by use of a telomeric repeat amplification protocol assay. RESULTS: Telomere length in mammary gland tumors ranged from 11.0 to 21.6 kilobase pairs (kbp; mean +/- SEM, 14.5+/-0.5 kbp) but did not differ among tumor types. Telomeres in mammary gland tumors were slightly shorter than in normal tissue specimens, but telomere length could not be directly compared between groups, because mean age of dogs was significantly different between groups. Age was negatively correlated with telomere length in control dogs but was not significantly correlated with length in affected dogs. Telomerase activity was detected in 26 of 27 mammary gland tumors and in 4 of 12 normal tissue specimens. However, telomerase activity and telomere length were not correlated in tumor specimens. CONCLUSIONS AND CLINICAL RELEVANCE: Telomere length is maintained in canine mammary gland tumors regardless of the age of the affected dog. Measurement of telomere length may be a useful tool for monitoring the in vivo effects of telomerase inhibitors in dogs with tumors.     

Phytogeny and Cross-infectivity of Powdery Mildew Isolates (Podosphaera fuliginea s. lat.) on Cosmos and Cucumber

To clarify the relationship between the phylogeny and infectivity of isolates of Podosphaera fuliginea s. lat. (= Sphaerotheca fuliginea s. lat.) from cosmos and cucumber, more than 50 powdery mildew isolates from these two plants were subjected to nucleotide sequencing or PCR-RFLP analysis of the rDNA internal transcribed spacer (ITS) region and cross-inoculation tests. The isolates from both cosmos and cucumber are genetically monotypic, and there are six nucleotide substitutions in the rDNA ITS region between isolates from cosmos and cucumber. Cross-inoculation tests of these isolates revealed that isolates from cosmos are not pathogenic on cucumber. Although isolates from cucumber produced conidia on leaves of cosmos in the laboratory, the conidial density was much lower than that from isolates from cosmos. This result, as well as the fact that the cucumber strain was not isolated from cosmos in fields, suggests that isolates from cucumber do not infect cosmos in the field. Therefore, powdery mildews on cosmos and cucumber can be regarded to have become specialized for their hosts both genetically and pathogenically. The present study reconfirms the close relationship between phylogeny and infectivity of powdery mildew fungi. Host specialization may be a trigger that causes genetic divergence of powdery mildew fungi. Received 28 June 2000/ Accepted in revised form 4 September 2000     

Peripheral neuroblastoma in a young labrador retriever

A 2-year-old Labrador Retriever developed atrophy of the right temporal muscle, subsequently showed generalized seizure and died 2 months after the clinical onset. Postmortem examination revealed the tumor masses in the right mandibulopharyngeal area, nasopharynx and intracranial space. Histopathologically, these tumor masses were composed of small round neoplastic cells and neuropil-like stroma separated by fibrovascular septa. In the neoplastic masses, small neoplastic cells with round to oval hyperchromatic nuclei and scanty cytoplasm predominated, and angulated neoplastic cells with larger nuclei and moderate cytoplasm were scattered. Immunohistochemically, neoplastic cells were positive for neuron specific enorase, neurofilament protein, chromogranin A, synaptophysin and tyrosine hydroxylase. Based on these findings, this case was diagnosed as peripheral neuroblastoma, presumably originated from the sympathetic ganglion, maybe right craninal cervical ganglion.