Interannual variability in stock abundance of the neon flying squid, Ommastrephes bartramii, in the North Pacific Ocean during 1979–1998: impact of driftnet fishing and oceanographic conditions

Variability in catch-per-unit-effort (CPUE) was examined for the autumn cohort of Ommastrephes bartramii collected with research driftnets during 1979–1998 along five longitudinal transects passing through the Subarctic, Transitional and Subtropical Domains in the North Pacific. CPUE was generally low during the period of intensive commercial driftnet fishing (1980–1992) and increased following the 1992 moratorium on the use of large-scale driftnets. However, CPUE levels were low for the cohorts hatched in 1992 and 1996 (captured in subsequent years owing to a one-year life of O. bartramii ) that experienced low sea surface temperatures from hatching to recruitment. Among similar-aged squid collected from 180° and 179°30'W in June, mantle lengths were significantly greater in 1997 than during 1995–96. These findings suggest that the driftnet fishery and sea surface temperatures from hatching to recruitment strongly affected stock abundance and possibly growth.     

Development and application of fluorescence in situ hybridization (FISH) method for simple and rapid identification of the toxic dinoflagellates Alexandrium tamarense and Alexandrium catenella in cultured and natural seawater

ABSTRACT:   The toxic dinoflagellates Alexandrium tamarense (Lebour) Balech and A. catenella (Whedon and Kofoid) Balech produce potent neurotoxins, such as saxitoxin and gonyautoxin and have been mainly responsible for paralytic shellfish poisoning (PSP) in Japan. To prevent a negative effect on the fishery industry, it is necessary to identify these toxic species precisely and rapidly before and during the bloom. In this paper, a rapid and simple protocol of a fluorescence in situ hybridization (FISH) method using ribosomal RNA (rRNA)-targeted probes has been established for identifying the cultured strains and natural cells of A. tamarense and A. catenella . Using the FISH method established in this study, it was possible to identify these toxic species species-specifically and rapidly, within 30 min. The procedure of detection constituted three steps: (i) fixation/dehydration; (ii) hybridization; and (iii) washing; this made the identification simple. Moreover, this method did not require either special techniques or equipment, and the cost for detection was low. The specificity, rapidity, and simplicity of the developed method suggest that it might be useful for routine monitoring of these toxic microalgae.     

Paralytic shellfish poisoning toxin analysis of the genus <Emphasis Type="Italic">Alexandrium</Emphasis> (Dinophyceae) occurring in Korean coastal waters

ABSTRACT:   Paralytic shellfish poisoning (PSP) toxins produced by Alexandrium isolates from Korea were analyzed by high-pressure liquid chromography. Species designation of the regional isolates was determined by morphological criteria and ribotyping inferred from sequences of the 28S rDNA D1-D2 region. Toxin analysis performed at the exponential growth phase, revealed that the two strains of A. fraterculus were non-toxic, while the strains of A. tamarense and A. catenella were toxic. Toxic isolates DPC7 and DPC8 of A. catenella produced GTX1, 2, 3, 4, 5, dcGTX2, 3, C1, 2, neoSTX and STX with trace or non-detectable levels of C3 and C4, while isolates UL7, KDW981, SJW97043, SJW97046, KJC97111 and KJC97112 of A. tamarense produced GTX1, 2, 3, 4, dcGTX3, C1, 2, neoSTX with trace or non-detectable levels of C3, 4, dcSTX and STX, and no GTX5 and dcGTX2. The major toxins produced by A. catenella were C1 +2, and those of A. tamarense were C1 +2 and GTX4 in most of the isolates. A. tamarense strains other than SJW97046 produced a relatively high proportion of carbamate toxins, reflecting the high toxicity scores of shellfish intoxication in sampled coastal areas. Two representative toxic isolates, A. tamarense SJW97043 and A. catenella DPC7, were cultured for 30 days in batch mode and subjected to toxin analysis at 5-day intervals. Comparison of toxin productivity in terms of total toxin content, toxin components, and their variations with culture age revealed marked differences between the two strains.     

Purified Culture Systems for Bovine Oviductal Stromal Cells

Isolated stromal cells from the ampullary and isthmic parts of bovine oviductal tissues were cultured in monolayer and spheroid (cell aggregate) systems. Prostaglandin F2α (PGF) plays a crucial role in oviductal contraction and is produced by oviductal epithelial cells in cattle. Since stromal cells of many organs produce PGF, PGF production by bovine oviductal stromal cells was investigated. After PGF synthesis was confirmed, the utility of isolation and culture methods for oviductal stromal cells was evaluated by PGF production in the present study. The homogeneity of the cells was > 99%. PGF production of the cells was increased by tumor necrosis factor-α. The stromal cells aggregated and formed a spheroid by the treatments with several reagents. PGF production was higher in the spheroid culture than in the monolayer culture. The isolation and culture methods described here will facilitate studies of the physiological function of bovine oviductal stromal cells.     

Development of a quantification assay for the cysts of the toxic dinoflagellate <Emphasis Type="Italic">Alexandrium tamarense</Emphasis> using real-time polymerase chain reaction

ABSTRACT:   The cysts of toxic dinoflagellate Alexandrium tamarense are the seed population for the bloom responsible for paralytic shellfish poisoning (PSP). However, it is impossible to identify the Alexandrium spp. cyst on the basis of morphological features. In this study, we prepared A. tamarense cysts by sexual conjugation in laboratory conditions and developed an efficient DNA extraction method for polymerase chain reaction (PCR) assay. Using the A. tamarense cysts, we established the identification and quantification method showing the species specificity and the high sensistivity for A. tamarense cysts using real-time PCR. This assay was also able to detect and quantify the A. tamarense cysts accurately when mixed with excess cysts of A. catenella (Whedon and Kofoid) Balech prepared by conjugation experiment.     

Activities of mesencephalic nucleus neurons during fictive swimming of the carp Cyprinus carpio

ABSTRACT:   Fish swim by undulatory contractions of the axial trunk musculature. It has been presumed that a descending signal from the brainstem activates central pattern generators in the spinal cord to make the swimming rhythm. In the carp the electrical or chemical stimulation of a mesencephalic nucleus, the nucleus fasciculi longitudinalis medialis (Nflm), could initiate swimming. However, it has not been established what signals originate from the Nflm in order to make the fish swim. The activity of the Nflm neurons was therefore examined electrophysiologically during fictive swimming in paralyzed carp. Three types of neuronal activities closely related to the swimming rhythms were obtained. The first type was a continuous tonic firing throughout an episode of fictive swimming. Neurons involved in this tonic activity may project to the spinal cord and contribute to the activation of spinal neurons to initiate fish swimming. The second type was accompanied by continual phasic firings occurring in rhythm with the activity of spinal motoneurons. Supposing that the swimming rhythm originates in the spinal cord, the synchronous activity in the brain neurons may suggest that in the nucleus there is a relay neuron conveying the rhythm information from the cord to other neurons there or in the brain. The third type exhibited reduced firing rates during fictive swimming. It is possible that the neurons engaged in this activity may be inhibitory and suppress the activities of other neurons in the nucleus and spinal cord during rest or during decelerating swimming.     

Extended glucuronidation is another major path of cyanidin 3-O-beta-D-glucopyranoside metabolism in rats

We previously determined that five rather hydrophobic metabolites appeared in blood plasma after oral administration of cyanidin 3-O-beta-D-glucopyranoside, but a group of hydrophilic metabolites still remained unidentified. In the present study, 12 hydrophilic metabolites found were collected from urine and plasma samples by high-performance liquid chromatography (HPLC) and then analyzed by tandem MS spectrometry. From the MS spectra, four metabolites out of 12 were assigned as glucuronides of cyanidin 3-O-beta-D-glucopyranoside and six out of 12 were glucuronides of the primary metabolites of cyanidin 3-O-beta-D-glucopyranoside (O-methyl cyanidin 3-O-beta-D-glucopyranoside). Extended glucuronides of cyanidin 3-O-beta-D-glucopyranoside and O-methyl cyanidin 3-O-beta-D-glucopyranoside showed their maximum plasma concentrations at 15 and 60 min (or 30 min) after oral administration, respectively. Their maximum plasma concentrations ranged from 15 to 70 nM. From the profile of urinary-excreted anthocyanins after intravenous administration, it was deduced that extended glucuronides of cyanidin 3-O-beta-D-glucopyranoside and O-methyl cyanidin 3-O-beta-D-glucopyranoside were mainly produced in the liver rather than by intestinal flora. The area under the plasma concentration curve was 0.25 micromol min/L for extended glucuronides of cyanidin 3-O-beta-D-glucopyranoside and 0.14 micromol min/L for O-methyl cyanidin 3-O-beta-D-glucopyranoside, respectively, when evaluated as cyanidin 3-O-beta-D-glucopyranoside equivalent, indicating that extended glucuronidation is a critical pathway in cyanidin 3-O-beta-D-glucopyranoside metabolism in rats.     

Fine surface structure of bovine acrosome-intact and reacted spermatozoa observed by atomic force microscopy

The atomic force microscope (AFM) provides nanometer resolution, topographic data of the natural surface structure of materials. We studied the topology of the surface structure of bovine sperm heads during the acrosome reaction by AFM. In addition, we numerically analyzed the areas of the median sagittal plane of the sperm heads. Bovine frozen-thawed spermatozoa were washed, capacitated by heparin, and incubated with lysophosphatidylcholine (LPC) to induce the acrosome reaction, smeared on a cover glass, air-dried, and observed with AFM using the dynamic force (tapping) mode. AFM analysis of spermatozoa showed the clear surface structure of acrosomes, equatorial segments, postacrosomal regions and necks. Although AFM images of spermatozoa capacitated by heparin had complete acrosomes, most spermatozoa treated with LPC had no acrosomal caps as shown by AFM. These observations coincided with those obtained by light microscopy after staining with naphthol yellow S and erythrosin B. Furthermore, numerical analysis of AFM images indicated that areas of the median sagittal plane of the anterior portions of acrosome-reacted sperm heads (2679 +/- 616 pixels) were approximately 40% less than those of intact heads (4535 +/- 174 pixels, P<0.05). These results indicate that AFM can usefully observe and numerically analyze the fine surface structures of bovine spermatozoa.