菊地 元史

During aging, the male Japanese quail exhibits a loss of fertility, increased morphological abnormalities in the testes, and a higher incidence of Sertoli cell tumors. Although there is a co-incident loss of reproductive behavior, plasma androgen levels remain high until testicular regression occurs in association with senescence. The purpose of this study was to compare mean specific binding of chicken luteinizing hormone (LH) and follicle-stimulating hormone (FSH) as a measure of testicular receptors during identified stages during aging. Males were categorized according to age (young = 9 months, middle aged = 24 months, or old = 36+ months) and sexual behavior (active or inactive). Testicular samples were collected immediately after perfusion with 4% paraformaldehyde from the following groups: young active (n = 8), young photoregressed (n = 5), young photoregressed plus testosterone implant (n = 4), middle-aged active (n = 8), middle-aged inactive (n = 4), old inactive (n = 5), and old inactive plus testosterone implant (n = 6). A crude plasma membrane fraction was prepared from the testes of each bird and an aliquot deriving from 10 mg of testicular tissue was used for binding assay. Specific binding of labeled LH or FSH was expressed as percentage of total radioactive hormone. Results showed significant (P < 0.05) age-related decreases in both FSH and LH receptor numbers. The highest FSH binding was found in young and middle-aged active males, with low binding in old inactive males. Testicular LH binding decreased during aging, with a sharp decrease in middle-aged males, which was similar to old males. Testosterone implants weakly stimulated FSH and LH binding in old males. Both LH and FSH binding decreased in photoregressed young males. However, testosterone implants stimulated increased LH binding, but did not affect FSH binding in young photoregressed males. These results provide evidence for separate regulation of testicular LH and FSH receptors, with testosterone stimulation of LH receptor, but not FSH receptor number in young males. However, during aging there appears to be a loss of this response, potentially because of the reduced efficacy of testosterone stimulation, thereby implying a diminished capacity for response with aging.

鳥類の性判別法として,性染色体上に存在するCHD(chromodomain helicase DNA binding protein)遺伝子を解析する方法が有用である。トキ(Nipponia nippon)のZおよびW染色体上のそれぞれのCHD遺伝子について特定領域の塩基配列を決定した。両者の間には数箇所のヌクレオチドの変異が見られた。これにより,PCR法によって試料中のCHD遺伝子の特定領域を増幅し,そのPCR産物を制限酵素解析することによって性を判別する方法をトキにも応用できることが明らかとなった。この方法を用いて,1999年に中国より贈られたつがいのトキから,佐渡トキ保護センターにおいて,1999年,2000年に産まれた計3羽の雛の性判別を行なった。DNAの抽出のための試料として,羽軸に付着した細胞の他,孵化後の卵殻内に残された胚由来の組織が有効であった。

We examined the topographic cell affinity of different types of hormone-producing cells in the rat anterior pituitary gland. Pituitaries were removed from 8-10 week-old male SD rats, and were fixed in sublimate-formalin. The 40 μm sections were obtained with a Microslicer, then double-immunolabeled (FITC and TexasRed methods) using antibodies against five types of pituitary hormones. Topographic affinity was examined three-dimensionally using a confocal microscope, and was expressed as attachment rate. Statistical analysis revealed that the different types of hormoneproducing cells did not exist at random locations in the gland, but rather showed specific topographic affinities. The following pairs of cell types were observed to have significantly high affinities: LH and PRL cells, ACTH and GH cells, and TSH and GH cells. In contrast, the following pairs of cell types were observed to have no significant affinities: GH and PRL cells, ACTH and LH cells, TSH and LH cells, ACTH and TSH cells, and cells of the same type. These specific topographic affinities between different types of anterior pituitary cells may be intimately related to cell-to-cell interactions in the gland.

A variety of orientation cues has been suggested for the migration to the breeding site in adult amphibians. We categorized the cues into the following 3 groups: 1) cues from the breeding pond such as male calling and pond odors, 2) celestial cues such as the sun light and the magnetic field of the earth and 3) cues from the area or route of the migration which compose a local map such as a visual and olfactory maps. To determine which of these is used by the toad, Bufo japonicus, we designed and conducted a displacement experiment in which migrating toads from one direction were transported to the ground in the opposite side of the pond. The displaced toads were completely disoriented and moved to random directions. We conclude that the toad uses a local map) to orient to the breeding pond and cues from celestial bodies and the pond are not used. We also found that adult toads tracked the same route on both trips from and to the pond. This suggests that the local map was memorized by newly metamorphosed toads at their first terrestrial trip from the pond. The next step of our study was to determine what sense is used to receive the cue . We found blind toads, whose upper and lower eye-lids were stitched together, could reach the pond at a similar rate with the sham-operated and intact toads. However, anosmic toads, whose olfactory mucosa were damaged by the treatment with a 5% silver nitrate solution, rarely reached the pond. Tracking experiments with blind toads and toads bearing a bar magnet on their heads revealed that neither blindness nor the magnet had any effect on either the direction or distance of the migration to the pond. In contrast, anosmic toads could not orient properly and moved in random directions. We speculate that newly metamorphosed toadlets remember the route or area of their first terrestrial migration by using the olfactory sense. In the spring, two to three years later, they start their breeding migration to the home pond by using a local olfactory map and reverse tracking of the memorized route.