Significance of local immunity in hen reproductive organs

The current paper describes aspects of local immunity in the ovary and oviduct, and the significance of immunity to reproductive functions in hens. The immunocompetent cell populations in the ovary and oviduct change with a positive correlation to sexual activity, and gonadal steroid is one of the key factors in the increase. Local immune responses mediated by major histocompatibility complex class II and T cell subsets occur in response to infection by Salmonella enteritidis, which may contaminate eggs. In the ovary, immunocompetent cells are also suggested to play roles in the regulation of ovarian functions. Macrophages and T cells are likely to enhance the regression of atretic follicles to maintain the ovarian tissue microenvironment. Autoantibodies to ovarian tissues appeared in the hens with low egg laying frequency, suggesting that the auto‐antibodies may be one of the factors in the decline of egg production. In the oviduct, local immunity possibly has a role in the selection of sperm, though the immunoreactions may also affect sperm survival leading to the decline in fertility. The concentration of yolk IgY, which plays a role in maternal immunity transmission, significantly decreases with the aging of birds, whereas it is significantly increased by estrogen. Therefore, the immune system plays significant roles not only in defense against infection, but also in the functions of reproductive organs. Investigations on the local immune system in the reproductive organs and factors affecting it are of importance for the production of sterile eggs and improvement of reproductive functions.     

Changes in the expression of toll-like receptor mRNAs during follicular growth and in response to lipopolysaccharide in the ovarian follicles of laying hens

The aim of this study was to determine the changes in the mRNA expression of Toll-like receptors (TLRs) in hen ovarian follicles during follicular growth and in response to lipopolysaccharide (LPS). White follicles and the fifth largest to largest follicles (WF and F(5)-F(1), respectively) were collected from laying hens. To examine the effects of LPS, the laying hens were treated intravenously with LPS (1 mg/kg BW) 0, 3, 6, 12 and 24 h before examination. Expressions of TLRs and IL-1beta in the theca and granulosa layers were examined by semi-quantitative RT-PCR. Immunocytochemistry was performed to identify immunoreactive TLR-4. The theca layer expressed TLR-2, TLR-4, TLR-5 and TLR-7, whereas the granulosa layer expressed only TLR-4 and TLR-5. The expression of TLR-4 and TLR-5 in the theca layer increased significantly during follicular growth. In the granulosa layer, the expression of TLR-5 increased, but that of TLR-4 was unchanged. Expression of TLR-4 increased significantly during the period of 6 to 12 h of LPS treatment in the theca layer and during the period of 12 to 24 h in the granulosa layer of F(3). Immunoreaction products for TLR-4 were observed in theca interna and granulosa layers of WF and F(5)-F(1), with the greater amount observed in the theca interna. LPS treatment significantly increased expression of IL-1beta in the theca layer after 3 h and in the granulosa layer during the period of 12 to 24 h. These results suggest that TLRs are expressed in ovarian follicles and that TLR-4 and TLR-5 expression increase with the growth of follicles. Enhanced expression of TLR-4 and IL-1beta by LPS in the theca and granulosa layers suggests possible roles of TLR in recognition of microorganisms.     

Developmental changes in pituitary–thyroid axis, and formation of gonads in leptocephali and glass eels of Anguilla spp.

SUMMARY: Pituitary, thyroid gland and gonads in leptocephali of Japanese eel Anguilla japonica (19.8–32.6 mm in total length), A. obscura (45.0 mm), and A. bicolor pacifica (49.5 mm) and those in glass eels of the Japanese eel were histologically and immunohistochemically examined in order to observe the developmental changes of these endocrine organs in the Anguillidae. The pituitary, consisting of adenohypophysis and neurohypophysis in Japanese eel leptocephali over 22.5 mm, did not contain thyroid stimulating hormone (TSH) immunoreactive cells. Such cells were, however, detectable in the more developed pituitaries of leptocephali of A. obscura and A. bicolor pacifica and in those of glass eels. Conversely, thyroxine (T₄)-immunoreactive thyroid follicles could be detected in all specimens, both leptocephalic and glass eel. Only in glass eels, gonads were found in the body cavity, and these gonads harbored one or two primordial germ cells (PGC) per cross-section. Our results indicate that thyroid hormones (TH) production started prior to TSH production, and that TSH and TH are both secreted during the metamorphosis from leptocephalus to glass eel. Therefore, it is plausible that the TSH–TH axis is involved in the metamorphosis from leptocephalus to glass eel, but not in the early growth from preleptocephalus to leptocephalus.     

The duality of teleost gonadotropins

The duality of salmon gonadotropins has been proved by biochemical, biological, and immunological characterization of two chemically distinc gonadotropins. GTH I and GTH II were equipotent in stimulating estradiol production, whereas GTH II appears to be more potent in stimulating maturational steroid synthesis. The ratio of plasma levels and pituitary contents of GTHs and the secretory control by a GnRH suggest that GTH I is the predominant GTH during vitellogenesis and early stages of spermatogenesis in salmonids, whereas GTH II is predominant at the time of spermiation and ovulation. GTH I and GTH II are found in distinctly separate cells. In trout, GTH I is expressed first in ontogeny, whereas GTH II cells appear coincident with the onset of spermatogenesis and vitellogenesis, and increase dramatically at the time of final reproductive maturation. Comparison of the amino acid sequences of polypeptides and the base sequences of cDNA revealed that salmon GTH I β is more similar to bovine FSHβ than bovine LHβ and salmon GTH II β shows higher homology to bovine LHβ than to bovine FSHβ. The existence of two pituitary gonadotropins in teleosts as well as tetrapods suggests that the divergence of the GTH gene took place earlier than the time of divergence of teleosts from the main line of evolution leading to tetrapods.     

Quality aspect of fish sauce prepared from underutilized fatty Japanese anchovy and rabbit fish

ABSTRACT:   To explore the potential utility of underutilized fish in the fish sauce industry, fish sauces were prepared from both raw and heat-induced meat of Japanese anchovy Engraulis japonica and rabbit fish Siganus fuscescens using wheat malt, and their quality aspects and sensory properties were assessed. Proximate composition of the fish meat represents protein as the major component (16.0–17.8%), other than moisture. Analyses of free amino acids, peptides including oligopeptides, and organic acids contents in fish sauces revealed suitability of both raw and heat-induced meat of the selected species in commercial fish sauce production. The variations in taste of raw meat fish sauces were species-specific, but the taste of fish sauces from heat-induced meat were similar.     

Immunohistochemical detection of gonadotropin-like material in the hagfish pituitary, correlated with their gonadal conditions

In the present study, immunoreactive gonadotropin (GTH)-like material was examined in the hagfish pituitary, in correlation with their gonadal conditions. For this purpose, three species of hagfish, Myxine glutinosa, Eptatretus burgeri and Paramyxine atami, were used. In all species, GTH-like cells were observed in the adenohypophysis. They were stained with several antibodies to LH-related GTHs, such as ovine LHβ, human LHβ, bullfrog LH, and salmon GTHIIβ. In the subsequent study, the relationship between the amount of GTH-like material and gonadal conditions was examined in Paramyxine atami. The adenohypophysis of adult animals exhibited well-developing features, and about half of the adenohypophysial cells were stained intensely with anti-ovine LHβ. On the other hand, the adenohypophysis of juveniles exhibited less developed features with few or no cells stained with anti-ovine LHβ. These results suggest that a GTH-gonadal system is truly present in the hagfish.     

Role of free neuromasts in larval feeding of willow shiner Gnathopogon elongatus caerulescens Teleostei, Cyprinidae

ABSTRACT:   It has been reported that the larvae of willow shiner Gnathopogon elongatus caerulescens have many free neuromasts on their body surface. This study examined the ability of the willow shiner larvae to feed on zooplankton by mechanoreception by the free neuromasts. Feeding experiments using untreated larvae and larvae treated with streptomycin, which impairs free neuromast function, were conducted under light and completely dark conditions. The larvae were put into Petri dishes, then nauplii of Artemia salina were introduced. The average number of Artemia eaten by the larvae was expressed as the average ingestion rate of Artemia /10 min. The ingestion rate of Artemia for untreated larvae was 12.3 under light conditions and 10.6 Artemia /10 min. even in complete darkness. The ingestion rate in the larvae treated with streptomycin was 11 under light conditions and only 0.8 Artemia /10 min under dark conditions. The low rate in the treated larvae under dark conditions must be due to impairment by the streptomycin. Therefore, the high ingestion rate for the untreated larvae under dark conditions would be surely dependent on mechanoreception. The results indicate that larval willow shiner is able to feed on zooplankton under limited light conditions.     

Effect of shrimp head protein hydrolysates on the state of water and denaturation of fish myofibrils during dehydration

ABSTRACT:   To utilize fisheries waste products as food materials with functional properties, shrimp head protein hydrolysates (SHPH) from three species of shrimp, that is, Northern pink shrimp ( Pandalus eous ), Endeavour shrimp ( Metapenaeus endeavouri ) and Black tiger shrimp ( Penaeus monodon ), were produced by enzymatic hydrolysis using endopeptidase derived from Bacillus subtilis and exopeptidase derived from Aspergillus oryzae at a level of 0.1% (w/w). SHPH were rich in protein (90–91%) and amino acids (71–84%) but little fat (0.01–0.02%). The average molecular weight of SHPH was 300–1400. The effect of 5% SHPH (dry basis) addition on the state of water and denaturation of lizard fish myofibrils (Mf) during the dehydration process was evaluated by the desorption isotherm and the Ca-ATPase activity, and compared with the effect of sodium glutamate (Na-Glu). SHPH decreased the water activity and the Ca-ATPase inactivation, and increased monolayer sorbed water and multilayer sorbed water of Mf, although these effects of SHPH were smaller than those of Na-Glu. These findings suggest that the SHPH suppressed dehydration-induced denaturation of myofibrillar protein by stabilizing the hydrated water surrounding myofibrils.     

Immunolocalization of sex steroid receptors in the epididymis and ductus deferens of immature and mature Japanese Quail, Coturnix Japonica

The goal of this study was to determine whether in the Japanese quail the male genital tract contains receptors for progesterone, androgen and estrogen (PR, AR and ER, respectively), which have significant roles in reproductive functions, and whether their localization changes during sexual maturation. The epididymis and ductus deferens (middle and ampulla regions) of immature (approximately 30-day-old) and mature male Japanese quail were collected and frozen sections of them were immunostained for PR, AR and ER. The immunoreaction products for AR and PR were found in the nuclei of epithelial cells in the efferent ductules, epididymal duct, and the middle and ampulla regions of the ductus deferens of mature and immature birds. In the mature birds, the epithelial cells of the efferent ductules, epididymal duct, and the middle and ampulla regions of the ductus deferens were positive for ER, although some of the cells in the ductus deferens were negative. The epithelial cells of the ductules in the epididymis stained positive for ER, but the immunoreactions were negligible in the ductus deferens of immature birds. These results suggest that the epididymis and ductus deferens in quail possesses PR, AR and ER receptors. Each receptor is expressed before sexual maturation, although enhancement of ER expression may occur during maturation.     

Rates of chemical weathering of porous rhyolites: 5-year measurements using the weight-loss method

To examine the rate of chemical weathering, field experiments using microweight-loss techniques were carried out. Two kinds of porous rhyolite forming lava domes in Kozu-shima Island were selected: (1) a younger rock (weathering period is 2.6 ka) and (2) an older rock (20 ka). Both rocks seem to have been very similar in their initial composition and structure. They have, however, different properties in the present depending on the difference in weathering period. Rock tablets of these rhyolites with a diameter of 3.5 cm and a thickness of about 1 cm were enclosed in a nylon mesh bag and placed in a soil–bedrock interface on a hillslope of central Japan for over 5 years. The younger rock has a lower weight loss by about 0.5%, and the older rock has a higher weight loss of 3% to 5%. These results show that older rock has a higher rate of chemical weathering than in younger rock. This supports Oguchi et al.'s (Oguchi, T.C., Hatta, T., Matsukura, Y., 1994. Changes in rock properties of porous rhyolite through 40,000 years in Kozu-shima Island, Japan. Geogr. Rev. Jpn. 67A, 775–793 (in Japanese, with English Abstr.); Oguchi, T.C., Hatta, T., Matsukura, Y., 1999. Weathering rates over 40,000 years based on changes in rock properties of porous rhyolite. Phys. Chem. Earth (A) 24, 861–870.) finding that the rate of change in chemical properties appears to accelerate with weathering time.