Self-feeding behavior of yellowtail, Seriola quinqueradiata, in net cages: diel and seasonal patterns and influences of environmental factors

The self-feeding pattern of yellowtail, Seriola quinqueradiata, maintained in floating net cages was examined throughout a year, and the influence of seasonal changes of the photoperiod and water temperature on the feeding pattern was investigated. Two groups of 50 yellowtail (initial mean body weight about 50 and 80 g, respectively) were kept in two experimental net cages (2×3×4 m deep), with a self-feeding device installed on each. It was possible to maintain yellowtail in net cages using a self-feeder throughout almost a year. The number of daily food demands was greatly affected by the seasonal changes in water temperature. Yellowtail showed high self-feeding activity, above 18 °C; depressing water temperatures did not influence the activity when the water temperature was over 18 °C. However, the activity decreased when the water temperature fell below 18 °C. The feeding pattern in a 24-h period was greatly affected by the temporal changes in light intensity. Annual observations revealed that yellowtail showed generally crepuscular plus nocturnal feeding behavior and had two peaks of feeding activity a day. These peaks appeared at dawn and dusk; moreover, a clear association between the most active time of self-feeding and the period of the greatest change in light intensity was observed. The results suggest that a change in light intensity might stimulate the appetite of yellowtail or that there is a light level at which yellowtail prefer to eat.     

Interleukin-1beta reduces galactose transport in intestinal epithelial cells in a NF-kB and protein kinase C-dependent manner

Interleukins (IL), aside from their role in the regulation of the immune cascade, they have also been shown to modulate intestinal transport function. IL-1β is a potent inflammatory cytokine involved in many important cellular functions. The aim of this work was to study the in vitro effect of IL-1β on d-galactose transport across intestinal epithelia in rabbit jejunum and Caco-2 cells. The results showed that d-galactose intestinal absorption was diminished in IL-1β treated jejunum rabbits without affecting the Na⁺, K⁺-ATPase activity. The presence of IL-1 cell-surface receptors was confirmed by addition to tissue of a specific IL-1 receptor antagonist (IL-1ra). The cytokine did not inhibit either the uptake of d-galactose nor modified the sodium-glucose transport (SGLT1) protein levels in the brush border membrane vesicles, suggesting an indirect IL effect. The IL-inhibition was significantly reversed in the presence of inhibitors of protein kinase C (PKC) and mitogen-activated protein kinases (MAPKs). The proteasome selective inhibitor completely abolished the IL-effect. Furthermore, the cytokine inhibition on galactose transport related to NF-kB activation was also confirmed in Caco-2 cells. In summary, the direct addition of IL-1β to intestinal epithelia inhibits d-galactose transport by a possible reduction in the SGLT1 activity. This event may be mediated by several transduction pathways activated during the inflammatory processes related to several protein kinases and nuclear factor, NF-kB. The IL-effect is independent of hormonal milieu and nervous stimuli.     

Stimulation of butyrate production through the metabolic interaction among lactic acid bacteria, Lactobacillus acidophilus, and lactic acid-utilizing bacteria, Megasphaera elsdenii, in porcine cecal digesta

In this study, we examined the potential of Megasphaera elsdenii as a probiotic agent in combination with sodium gluconate. We also examined the combination of M. elsdenii with probiotic lactic acid bacteria (LAB), Lactobacillus acidophilus, to enhance butyrate production in the large intestine using a pig cecal in vitro model under the presence of sodium gluconate. Compared to the uninoculated control culture (with only diluted cecal digesta), the addition of M. elsdenii and LAB to the culture stimulated significantly the production of n‐butyrate (60% increase) and n‐valerate (50% increase) after 24 h incubation. n‐Butyrate is regarded as the most important short‐chain fatty acid in the large intestine because it stimulates the proliferation of epithelial cells, mucus release and water and mineral absorption. Therefore, lactate‐utilizing butyrate producers such as M. elsdenii play a significant role in supporting the health‐beneficial effects of lactogenic prebiotics and probiotics LAB. The potential of M. elsdenii as a probiotic was also suggested.     

Changes in shoot allometry with increasing tree height in a tropical canopy species,Elateriospermum tapos

Allometry of shoot extension units (hereafter termed "current shoots") was analyzed in a Malaysian canopy species, Elateriospermum tapos Bl. (Euphorbiaceae). Changes in current shoot allometry with increasing tree height were related to growth and maintenance of tree crowns. Total biomass, biomass allocation ratio of non-photosynthetic to photosynthetic organs, and wood density of current shoots were unrelated to tree height. However, shoot structure changed with tree height. Compared with short trees, tall trees produced current shoots of the same mass but with thicker and shorter stems. Current shoots with thin and long stems enhanced height growth in short trees, whereas in tall trees, thick and short current shoots may reduce mechanical and hydraulic stresses. Furthermore, compared with short trees, tall trees produced current shoots with more leaves of lower dry mass, smaller area, and smaller specific leaf area (SLA). Short trees adapted to low light flux density by reducing mutual shading with large leaves having a large SLA. In contrast, tall trees reduced mutual shading within a shoot by producing more small leaves in distal than in proximal parts of the shoot stem. The production of a large number of small leaves promoted light penetration into the dense crowns of tall trees. All of these characteristics suggest that the change in current shoot structure with increasing tree height is adaptive in E. tapos, enabling short trees to maximize height growth and tall trees to maximize light capture.     

Spraguea (Microsporida: Spraguidae) infections in the nervous system of the Japanese anglerfish, Lophius litulon (Jordan), with comments on transmission routes and host pathology

Anglerfish from the genus Lophius are a globally important commercial fishery. The microsporidian Spraguea infects the nervous system of these fish resulting in the formation of large, visible parasitic xenomas. Lophius litulon from Japan were investigated to evaluate the intensity and distribution of Spraguea xenomas throughout the nervous system and to assess pathogenicity to the host and possible transmission routes of the parasite. Spraguea infections in L. litulon had a high prevalence; all fish over 403 mm in standard length being infected, with larger fish usually more heavily infected than smaller fish. Seventy percent of all fish examined had some gross visible sign of infection. The initial site of development is the supramedullary cells on the dorsal surface of the medulla oblongata, where all infected fish have parasitic xenomas. As the disease progresses, a number of secondary sites typically become infected such as the spinal, trigeminal and vagus nerves. Fish with infection in the vagus nerve bundles often have simultaneous sites of infection, in particular the spinal nerves and along the ventral nerve towards the urinary bladder. Advanced vagus nerve infections sometimes form xenomas adjacent to kidney tissue. Spraguea DNA was amplified from the contents of the urinary bladders of two fish, suggesting that microsporidian spores may be excreted in the urine. We conclude that supramedullary cells on the hindbrain are the primary site of infection, which is probably initiated at the cutaneous mucous glands where supramedullary cells are known to extend their peripheral axons. The prevalence of Spraguea infections in L. litulon was very high, and infections often extremely heavy; however, no associated pathogenicity was observed, and heavily infected fish were otherwise normal.     

Development of an air-injection press for preventing blowout of particleboard I: effects of an air-injection press on board properties

An air-injection press was developed to prevent particleboard from blowing out during the manufacturing process. The air-injection press, which has holes punched in the heating plates, injects high-pressure air into the board through the holes of one plate and releases the air through the holes of the other plate. The high-pressure air forces out vapor trapped within the board, thus preventing blowout. The newly developed press reduced the pressing time required for manufacturing board from high-moisture-content particles. However, the manufactured boards exhibited mechanical properties and dimensional stability inferior to conventionally manufactured boards.     

Exclusion of polymeric immunoglobulins and selective immunoglobulin Y transport that recognizes its Fc region in avian ovarian follicles

In avian species, blood immunoglobulin (Ig) Y, the equivalent to mammalian IgG, is selectively incorporated into ovarian follicles, but other classes, IgA and IgM, are much less abundant in the follicles. Several mammalian Igs, including IgG and IgA, are also incorporated into ovarian follicles when administered to birds. To clarify the Ig structure required for incorporation into ovarian follicles, Ig uptakes were determined after the intravenous injection of chicken and human Igs. Three chicken Igs (cIgY, cIgA and cIgM) and two human IgAs (monomeric hIgA and polymeric hIgA) were labeled with digoxigenin, and their uptakes into quail (Coturnix japonica) egg yolks were determined by ELISA and SDS-PAGE. The uptake of cIgY was the highest among the three cIgs (22% of injected cIgY was recovered from egg yolks). Chicken IgA was efficiently incorporated into egg yolk when it formed a monomeric state. Pentameric IgM was untransportable into egg yolk. We also found that the uptake of monomeric hIgA was much more efficient than that of polymeric hIgA. These results suggest that the retention of the monomeric form contributes to the efficient transport of Igs into ovarian follicles. On the other hand, Ig uptakes among monomeric Igs nevertheless differed; for example, a time-course analysis showed that the rate of monomeric cIgY uptake was approximately eight times faster than that of monomeric hIgA. The injection of cIgY fragments Fc, Fab and F(ab')(2) resulted in the largest uptake of Fc fragment, with the same level as that of cIgY. These results suggest the presence of a selective IgY transport system that recognizes its Fc region in avian ovarian follicles.     

Rediscovery of a diploid cytotype of Dasypyrum breviaristatum in Morocco

The chromosome numbers of a total of 273 Dasypyrumbreviaristatum plants sampled from 20 Moroccan and one Greek naturalpopulations were examined. 270 plants from all of the populations weretetraploids. Among them, 223 were eu-tetraploids with 28 chromosomes and 47 wereaneuploids with 25, 27 and 29 chromosomes. Besides, three plants were found tobe diploids among 16 plants from a population in the Moyen Atlas Mountains ofMorocco. This is the second report of a diploid cytotype ofD. breviaristatum since the firstcommunication in 1957. Morphologically, the diploids were similar to but smallerthan the tetraploids in plant height, spike length, spikelet number and leafepidermis cell size. However, it was not possible to distinguish between the twocytotypes based on those morphological characteristics alone. A distinctdifference was found between the two cytotypes only in the number of trichomeson the leaf surfaces. The karyotype of the diploid cytotype consisted of a pairof SAT-chromosomes, five pairs of metacentric and a pair of submetacentricchromosomes. Based on the similarity in karyotype and in plant morphologybetween the two cytotypes of D.breviaristatum, we suggest that the diploid cytotype is themost probable candidate for the ancestral form of the tetraploid cytotype.     

Morphological and behavioral indicators of reproductive premolt females of the helmet crab Telmessus cheiragonus

Fisheries Science - Evaluation of the molting stage of crustaceans is essential for studying their mating behavior because of molt-dependent changes in their behavior. For example, in species in...