Ultrastructural characteristics of two distinct gonadotropes (GTH I- and GTH II-cells) in the pituitary of rainbow trout Oncorhynchus mykiss

The salmonid pituitary produces two chemically distinct gonadotropins (GTHI and GTHII). Ultrastructural characteristics of GTHI- and GTHII-producing cells were studied in the trout pituitary with electronmicroscopic immunocytochemistry using antisera against salmon GTHIβ- and IIβ-subunits. In pituitaries from vitellogenic fish, GTHI-cells were characterized by numerous dilated cisternae of the granular endoplasmic reticulum (GER) and a small number of Iβ-positive granules (diameter, 100–300 nm), whereas GTHIIβ-immunoreactivity was found on granules (diameter, 200–400 nm) and large globules (diameter, 500–4000 nm) in apparently different cells (GTHII-cells). Distinct cellular distributions of GTHI and GTHII were maintained during gametogenesis, although morphological characteristics of GTHI- and GTHII-cells overlapped each other due to changes in number and size of the granules, globules and cisternae of the GER. Interestingly, the globules in the GTHI-cells were immunonegative for GTHIβ, although in the GTHII-cells they were always stained with GTHIIβ-antiserum. These results confirm that GTHIβ and GTHIIβ are synthesized in distinctly different cell-types in the salmonid pituitary and indicate that morphological characteristics cannot be used to distinguish these two cell-types.

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Résumé L'hypophyse des salmonidés produit deux gonadotropines (GTHI et GTHII) chimiquement distinctes. Les caractéristiques ultrastructurales des cellules produisant la GTHI et la GTHII ont été étudiées par immunocytochimie en microscopie électronique en utilisant des anticorps dirigés contre les sousunités GTHIβ et GTHIIβ de saumon. Chez les poissons en vitellogenèse, les cellules à GTHI se caractèrisent par un réticulum endoplasmique granulaire (REG) contenant de nombreuses citernes dilatées et un petit nombre de granules positives à la GTHIβ (diamètre 100–300 nm) tandis qu'une immunoréactivité à la GTHII était trouvée sur des granules (diamètre 200–4000 nm) et de grands globules (diamètre 500–4000 nm) dans des cellules apparemment différentes (cellules à GTHII). Des distributions cellulaires distinctes de la GTHI et la GTHII se sont maintenues à des stades plus avancées de la gamétogenèse, bien que les caractéristiques morphologiques des cellules à GTHI et GTHII se recoupent suite à des changements dans le nombre et la taiile des granules, des globules et des citernes du REG. II est à remarquer que les globules prśents dans les cellules à GTHI étaient immunonégatifs à la GTHIβ alors que dans les cellules à GTHII ils étaient toujours marqués par l'anticorps contre la GTHIIβ. Ces résultats confirment que, dans l'hypophyse des salmonidés, les GTHIβ et GTHIIβ sont synthetisées dans des types cellulaires différents et indiquent que des caractéristiques morphologiques ne peuvent être utilisées pour distinguer ces deux types cellulaires.

     

Utilization of wood cell wall components

This article summarizes current utilizations of wood cell wall components in relation to biorefinery of woody biomass as a separation method of its constituents. Especially, utilization of isolated lignins, involving transformation and molding, are demonstrated with respect to productions of carbon fibers and their further functionalization, such as developments of activated carbon fibers and electrodes for second battery and electric double-layer capacitor.     

Preparation of activated carbon fibers with large specific surface area from softwood acetic acid lignin

Softwood acetic acid lignin (SAL) free from a high-molecular-mass fraction could be spun at 220°C by a spinning machine equipped with an extruder. Although the resulting fibers required thermostabilization, this step could be conducted with a faster heating rate than that for fibers obtained from hardwood acetic acid lignin (HAL). The thermostabilized SAL fibers were converted to activated carbon fibers (ACF) by carbonization in a stream of nitrogen at 1000°C, followed by steam activation at 900°C. At an activation time of 40 min, the SAL-ACF had a larger specific surface area than the corresponding HAL-ACF. When the activation time for SAL carbon fibers was prolonged to 80 min, the adsorption capacities of resulting ACF against iodine and methylene blue were markedly increased, as was the surface area of the ACF. It was found that SAL-ACF had adsorption properties comparable to those of high-performance commercial ACF. Also, it had a tensile strength equal to that of a pitch-derived ACF.Part of this work was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999     

Ontogenic and morphological study of gonadal formation in genetically-modified sex reversal XYPOS mice

Mammalian sexual fate is determined by the presence or absence of sex determining region of the Y chromosome (Sry) in the “bipotential” gonads. Recent studies have demonstrated that both male and female sexual development are induced by distinct and active genetic pathways. Breeding the Y chromosome from Mus m. domesticus poschiavinus (POS) strains into C57BL/6J (B6J) mice (B6J-XY^POS) has been shown to induce sex reversal (75%: bilateral ovary, 25%: true hermaphrodites). However, our B6N-XY^POS mice, which were generated by backcrossing of B6J-XY^POS on an inbred B6N-XX, develop as males (36%: bilateral testis with fertility as well as bilateral ovary (34%), and the remainder develop as true hermaphrodites. Here, we investigated in detail the expressions of essential sex-related genes and histological features in B6N-XY^POS mice from the fetal period to adulthood. The onsets of both Sry and SRY-box 9 (Sox9) expressions as determined spatiotemporally by whole-mount immunohistochemistry in the B6N-XY^POS gonads occurred 2–3 tail somites later than those in B6N-XY^B6 gonads, but earlier than those in B6J-XY^POS, respectively. It is possible that such a small difference in timing of the Sry expression underlies testicular development in our B6N-XY^POS. Our study is the first to histologically show the expression and ectopic localization of a female-related gene in the XY^POS testes and a male-related gene in the XY^POS ovaries. The results from these and previous experiments indicate that the interplay between genome variants, epigenetics and developmental gene regulation is crucial for testis development.     

Food allergens inducing a lymphocyte-mediated immunological reaction in canine atopic-like dermatitis

Canine atopic-like dermatitis (ALD) is suspected to be associated with food allergies, particularly those mediated by lymphocytes. In this study, 54 cases were included as ALD dogs, based on the negative IgE test results. In the dogs, the percentage of activated cells in helper-T lymphocytes was measured by flow cytometry using cultured peripheral lymphocytes under food allergen stimulation. We observed that 49 of the 54 ALD dogs (90.7%) had positive lymphocyte reactions against one or more food allergens. The most common food allergen was soybean, showing positive results in 21 dogs (42.9%), while the allergen to cause the lowest number of reactions was catfish (only 5 dogs, 10.2%). These results may be useful in considering elimination diets for ALD dogs.     

Activated carbon sheet prepared from softwood acetic acid lignin

As an example of activated carbon (AC) moldings, AC sheets were prepared from thermoplastic acetic acid lignin by lamination. The resulting AC sheets are a new type of product that can be applied as water and air cleaners. Powdered softwood acetic acid lignin (SAL) was molded into sheets by a thermal pressing method. When the sheet was carbonized under a stream of nitrogen at 1000°C, it was deformed with expansion and contained much foam. The deformation during carbonization was suppressed by the addition of pulp to the lignin. A sheet prepared by mixing lignin with pulp was directly carbonized without thermostabilization. The carbonized sheet was activated with steam for 2h. The resulting AC sheet had adsorption properties, such as specific surface and iodine adsorption capacity, comparable to those of commercial AC powders or granules. Furthermore, the AC sheet had a larger capacity to adsorb methane than did the commercial AC powder. Therefore, SAL seems to be a promising source for the AC moldings.     

Effects of high protein levels in concentrate feed during the early fattening stage on physico-chemical composition and sensory characteristics of M. longissimus in Japanese Black heifers

The effects that high levels of protein in concentrate feed has during the early fattening stage on physico-chemical composition and sensory characteristics of M. longissimus in Japanese Black heifers were investigated. Four sets (8 head) of identical twins of Japanese Black heifers were divided into two groups: a group fed high levels of protein in concentrate feed in the early fattening stage (HCP); and a control group. Moisture, fat, protein, cooking loss, Warner-Bratzler shear force and fatty acid composition of M. longissimus were similar in both groups. Levels of free amino acid (FAA), aspartic acid, glutamine, taurine and histidine were lower in the HCP group than in the control group ( P  < 0.05). Levels of glutamic acid, serine, asparagine, threonine and total FAA in the HCP group tended to be lower than in the control group ( P  < 0.1). There were no significant differences between the sensory characteristics (juiciness, tenderness, fattiness, flavor and overall acceptability) of the two groups. These results suggest that the use of high levels of protein in concentrate feed during the early fattening stage does not affect the sensory characteristics of Japanese Black beef, but does alter the FAA content.     

A novel preparation of microcast for wood micromorphology using polydimethylsiloxane without digesting cell wall

We developed a novel method for preparation of microcasts of wood with silicone elastomer (polydimethylsiloxane; PDMS). PDMS was so flexible and elastic that it was possible to isolate the microcasts by simply pulling them out of the mold without digesting the cell wall after the resin was cured for 2 days at room temperature. The casts of some cell wall sculptures, such as spiral thickenings and bordered pits, had high fidelity. By contrast, the casts of distinctly bordered pits and tails of vessel elements were often deformed or broken. Bars of scalariform perforation plates were always torn and remained in the resin casts. The microcast preparation using PDMS is useful for easy investigation of cell wall sculptures. It might be also useful for microfractography of bars of scalariform perforation plates.     

Ultrastructural study on the morphological changes in indigenous bacteria of mucous layer and chyme throughout the rat intestine

Indigenous bacteria in the alimentary tract are exposed to various bactericidal peptides and digestive enzymes, but the viability status and morphological changes of indigenous bacteria are unclear. Therefore, the present study aimed to ultrastructurally clarify the degeneration and viability status of indigenous bacteria in the rat intestine. The majority of indigenous bacteria in the ileal mucous layer possessed intact cytoplasm, but the cytoplasm of a few bacteria contained vacuoles. The vacuoles were more frequently found in bacteria of ileal chyme than in those of ileal mucous layer and were found in a large majority of bacteria in both the mucous layer and chyme throughout the large intestine. In the dividing bacteria of the mucous layer and chyme throughout the intestine, the ratio of area occupied by vacuoles was almost always less than 10%. Lysis or detachment of the cell wall in the indigenous bacteria was more frequently found in the large intestine than in the ileum, whereas bacterial remnants, such as cell walls, were distributed almost evenly throughout the intestine. In an experimental control of long-time-cultured Staphylococcus epidermidis on agar, similar vacuoles were also found, but cell-wall degeneration was never observed. From these findings, indigenous bacteria in the mucous layer were ultrastructurally confirmed to be the source of indigenous bacteria in the chyme. Furthermore, the results suggested that indigenous bacteria were more severely degenerated toward the large intestine and were probably degraded in the intestine.