Several possible spawning sites of the Japanese eel determined from collections of their eggs and preleptocephali

The spawning area of the Japanese eel is located at the southern part of the West Mariana Ridge in the western North Pacific, but their spawning events have not been observed. To further understand Japanese eel spawning ecology, an interdisciplinary research survey by the R/V NATSUSHIMA (NT14-09, 14 May–4 June 2014) was conducted to detect spawning sites based on the seamount, salinity front, new moon and third quadrant (spawning south of front, west of ridge) hypotheses. Attempts were made to film spawning events with underwater camera systems and to consider if eels might be detected in hydroacoustic observations. Although no Japanese eels or spawning events were video-recorded and no eel aggregations could be clearly identified acoustically, three eggs were collected at two stations in the third quadrant region at or just south of 13° N on 26 and 27 May. Three or four days later, newly hatched preleptocephali were collected at two stations far to the south, including 224 at a station > 160 km southwest of the egg catches, and a few preleptocephali were caught at two stations closer to the egg stations. The eggs and southern preleptocephali were from discrete spawning events, which indicated that at least two spawning sites occurred in May 2014.

     

Induction of larval metamorphosis in the sea cucumber Apostichopus japonicus by neurotransmitters

Larval metamorphosis inducers of the sea cucumber Apostichopus japonicus were screened from physiologically active compounds. Doliolaria larvae completed their metamorphosis to juveniles in 120 h when treated with 5–10 μM of dopamine and l-DOPA, and 50 μM of l-adrenaline and l-noradrenaline. Doliolaria larvae had to be exposed to dopamine or l-DOPA for at least 24 h. D1-like dopamine receptor antagonists SKF87566 and LE300 (10 μM) inhibited metamorphosis by dopamine. However, the D2-like dopamine receptor antagonists sulpiride and nemonapride (10 μM) did not inhibit the effect of dopamine. The results suggest that D1-like dopamine receptors are involved in larval metamorphosis of the sea cucumber A. japonicus.     

5-Bromodeoxyuridine (BUdR) and light inactivation of proliferating Mycobacterium bovis and Mycobacterium avium sensitized bovine lymphocytes

Maximum inactivation (83–98%) of proliferating Mycobacterium bovis and/or Mycobacterium avium sensitized bovine lymphocytes was obtained when the lymphocytes were treated with 10^?4 M of 5-bromodeoxyuridine (BUdR) and light. Inactivation was specific though not total whether the cultures were first stimulated with M. bovis PPD or M. avium PPD, though slightly higher inactivation resulted when cultures were first stimulated with M. bovis PPD. There was, however, a statistically significant suppression (P < 0.05) of the counts/min of cultures initially stimulated with either M. bovis PPD or M. avium PPD and later restimulated with either of the antigens after BUdR-light treatment. Thus experiments showed that inactivation occurs only to those cells responding by proliferation to a particular stimulant. There is a potential for the use of this assay for differentiating infection due to either M. bovis or M. avium if total inactivation of proliferating lymphocytes could be achieved.     

Levamisole potentiation of antigen specific lymphocyte blastogenic response in Brucella abortus exposed but nonresponsive cattle

Incubation of Brucella abortus (field strain) infected and strain 19 vaccinated bovine peripheral blood lymphocytes with B. abortus antigen and levamisole caused a consistently significant increase in [3H] thymidine uptake when compared to cultures without levamisole. Levamisole did not potentiate B. abortus-induced blastogenic response of lymphocytes from non-exposed cattle. A dose response study showed that 10 micrograms/culture induced maximum potentiation of B. abortus-induced lymphocyte stimulation. Using the 10 micrograms/well concentration of levamisole, further studies were conducted to determine the net potentiation of the blastogenic responses in lymphocytes from B. abortus (field strain) infected cattle. B. abortus strain 19 vaccinated but nonresponsive and non-exposed cattle. Levamisole significantly potentiated the B. abortus-induced lymphocyte blastogenesis in lymphocytes from unresponsive cattle.     

Bouillonamide: A Mixed Polyketide–Peptide Cytotoxin from the Marine Cyanobacterium Moorea bouillonii

The tropical marine cyanobacterium, Moorea bouillonii, has gained recent attention as a rich source of bioactive natural products. Continued chemical investigation of this cyanobacterium, collected from New Britain, Papua New Guinea, yielded a novel cytotoxic cyclic depsipeptide, bouillonamide (1), along with previously reported molecules, ulongamide A and apratoxin A. Planar structure of bouillonamide was established by extensive 1D and 2D NMR experiments, including multi-edited HSQC, TOCSY, HBMC, and ROESY experiments. In addition to the presence of α-amino acid residues, compound 1 contained two unique polyketide-derived moieties, namely a 2-methyl-6-methylamino-hex-5-enoic acid (Mmaha) residue and a unit of 3-methyl-5-hydroxy-heptanoic acid (Mhha). Absolute stereochemistry of the α-amino acid units in bouillonamide was determined mainly by Marfey’s analysis. Compound 1 exhibited mild toxicity with IC₅₀’s of 6.0 µM against the neuron 2a mouse neuroblastoma cells.     

Monocyte-induced potentiation of bovine fetal thymocyte mitogenic responses to concanavalin A

Peripheral blood monocytes significantly potentiated the mitogenic response of bovine fetal thymocytes to Concanavalin A as measured by incorporation of [3H] thymidine into cellular DNA. Mononuclear cells obtained from either normal or Mycobacterium bovis sensitized cattle were cultured with or without purified protein derivative (PPD) for 24 hours at which time bovine fetal thymocytes and concanavalin A were added. After 3 days of culture, both activated or non-activated monocytes significantly potentiated Con A-induced blastogenic responses. of monocytes from thymocyte cultures completely abrogated thymocyte responses to Concanavalin A.     

Glycosphingolipid receptors for pathogenic vibrios in intestines of mariculture fish

Vibrios are highly motile, facultatively anaerobic bacteria that are ubiquitous in aquatic environments and part of the normal intestinal microflora of healthy fish, but some species can cause vibriosis. The adherence of vibrios to host fish intestines is a significant event not only for their survival and growth, but also in terms of pathogenicity. However, the molecular mechanism underlying the adhesion of vibrios to the intestinal tract of fish is not fully understood. We report here the identification of intestinal glycosphingolipid (GSL) receptors to which pathogenic vibrios attach in typical mariculture fish. Thin-layer chromatography overlay assays using five species of ³⁵S-labeled vibrios and intestinal glycosphingolipids of seven species of mariculture fish revealed that all of the fish tested possessed GM3 (NeuAcα2-3Galβ1-4Glcβ1-1′Cer) and/or GM4 (NeuAcα2-3Galβ1-1′Cer) as major acidic intestinal GSLs and that all of the vibrios tested specifically adhered to GM3 and/or GM4. Our results demonstrate that these GSLs were able to function as a receptor for the various vibrios tested. Analysis of the relationship between sugar structure and receptor activity for vibrios revealed that ‘NeuAcα2-3Galβ1-’ is required at the non-reducing end of glycosphingolipids for the bacteria to attach.