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1.
T Hashizume T Sasaki S Nonaka T Hayashi M Takisawa M Horiuchi T Hirata E Kasuya 《Reproduction in domestic animals》2005,40(2):184-189
It has been reported that the posterior pituitary (PP) gland contains a potent, unknown prolactin (PRL)-releasing factor (PRF) in rats. PRFs are assumed to be produced in neurones located within the hypothalamus, and to be peptidergic in nature. However, little is known about PRFs in domestic animals. To characterize the PRF in the PP of domestic animals, the present study examined the PRL-releasing activity of an acidic extract from bovine PP (bPP) in vitro and in vivo in cattle. First, the PRL-releasing effect of bPP extract was compared with that of PRL-releasing peptide (PrRP), and thyrotropin-releasing hormone (TRH) from cultured bovine anterior pituitary cells. The extract significantly increased PRL concentrations in the culture medium, at doses of 0.002 and 0.02 eq./ml (one eq. is the PP extract from one animal), compared with the control (p < 0.05). PrRP failed to stimulate the release of PRL. TRH significantly increased PRL concentrations in the culture medium, at doses from 10(-9) to 10(-7) M, compared with the control (p < 0.05). The rate of increase in the PRL concentration, by 0.02 eq./ml bPP extract, was significantly greater than that in TRH (p < 0.05). Secondly, plasma PRL responses to the intravenous (i.v.) injection of bPP extract (0.5 eq./head), PrRP [3.59 mug/kg body weight (BW)], TRH (1 mug/kg BW), and a dopamine receptor antagonist (sulpiride, 0.1 mg/kg BW), were examined in calves. PrRP failed to stimulate PRL release; however, plasma PRL increased immediately following the injection of bPP extract, TRH and sulpiride. The PRL-releasing effect of i.v. injections of TRH and sulpiride was more potent than that of bPP extract. Finally, plasma PRL responses to the intra-hypothalamic injection of bPP extract were examined in calves. The intra-hypothalamic infusion (arcuate nucleus) of 0.0625 eq./head of bPP extract strongly stimulated PRL release in calves (p < 0.05). The present results show that PP contains a physiologically potent PRF in cattle. 相似文献
2.
Sward characteristics,nutritive value and choice by cattle of conterminous monocultures of centipedegrass (Eremochloa ophiuroides) and bahiagrass (Paspalum notatum) 下载免费PDF全文
Masahiko Hirata Toshiro Okuma Yuichiro Tanaka Manabu Tobisa 《Animal Science Journal》2016,87(5):674-680
In south‐western Japan, centipedegrass (Eremochloa ophiuroides; CG) offers a novel option for a warm‐season perennial for grazing use in areas where bahiagrass (Paspalum notatum; BG) can be grown. However, the potential of CG as a forage has not been fully explored because of the short history as a forage crop. We conducted four experiments to evaluate CG (cv. TifBlair) in comparison with BG (cv. Pensacola) in terms of sward characteristics, nutritive value and choice by animals. In each experiment, four Japanese Black cows (Bos taurus) were individually allowed to graze conterminous monocultures of CG and BG (5 × 10 m each) for 30 min. Irrespective of regrowth durations and fertilizer rates, CG was consistently shorter, leafier and denser, contained lower acid detergent fiber and cellulose, and was preferred or equally selected by cows, as compared with BG. Furthermore, CG maintained sufficient levels of crude protein (80–89 g/kg DM) to ensure voluntary intake of ruminant animals under extended regrowth? and without fertilizer, whereas BG failed to do so (65 g/kg DM). CG provided higher digestible dry matter than BG when crude protein concentration exceeded 86 g/kg DM. The results indicate advantages of CG as a forage. 相似文献
3.
Hashizume K Takahashi T Shimizu M Todoroki J Shimada A Hirata M Sato T Ito A 《The Journal of reproduction and development》2003,49(1):45-53
In vitro cell culture is a convenient tool for studying cellular mechanisms. In the present study, production of matrix-metalloproteinases (MMPs) in bovine endometrial (containing both epithelial and stromal cells) monolayer cells was examined. Blastocysts attached to the endometrial cells in a monolayer culture were examined for their effects on MMP-2 production. Initial attachment of blastocysts to the monolayer inhibited MMP-2 production by endometrial cells. But once trophoblast cells began to migrate into the endometrial cell layer, MMP-2 production increased, and at the same time MMP-9 production also became evident in the medium. In order to understand how blastocysts affected MMP-2 production, we examined the effect of progesterone, estradiol, insulin-like growth factors (IGFs), tumor necrosis factors (TNFs), and interferon-tau (IFN-tau) supplementation. It was IFN-tau that inhibited the production of MMP-2. In addition, progesterone at a lower dose appeared to inhibit MMP-2 production. Both TNF-alpha and TNF-beta strongly stimulated the production of MMP-2 and MMP-9, whereas IGFs had no effect. Based on these findings, it appears that conceptus has the capacity to inhibit MMP activity. 相似文献
4.
For better understanding wood hardness, we developed a new hand-operated hardness tester that works with Brinell's method. With this tester we investigated the hardness distribution of wood minutely using a 2mm diameter ball tip. The following results were obtained: (1) On preliminary examination with medium-density fiberboard, we found that the value of Brinell's hardness decreased with the increase in the tip ball's diameter but that it was almost constant with the indenting velocity. (2) By using a small diameter tip, the difference of the hardness became clearer between earlywood and latewood. (3) With radial and tangential sections, we obtained hardness distribution patterns similar to those of wood grain. It seems that the hardness distribution reflects the distribution of density on wood surfaces. 相似文献
5.
Tetsuji Ota Tsuyoshi Kajisa Nobuya Mizoue Shigejiro Yoshida Gen Takao Yasumasa Hirata Naoyuki Furuya Takio Sano Raul Ponce-Hernandez Oumer S. Ahmed Heng Sokh Vuthy Ma Eriko Ito Jumpei Toriyama Yukako Monda Hideki Saito Yoshiyuki Kiyono Sophal Chann Nang Ket 《Journal of Forest Research》2015,20(6):484-492
6.
7.
Using a salmon migration model based on the assumption that swimming orientation is temperature dependent, we investigated the determining factors of the migration of juvenile and immature chum salmon (Oncorhynchus keta) in the North Pacific. We compared the predictions of the model with catch data of immature and juvenile chum salmon collected by Japanese research vessels from 1972 to 1999. The salmon migration model reproduced the observed distributions of immature chum salmon and indicates that passive transport by wind‐driven and geostrophic currents plays an important role in the eastward migration of Asian salmon. These factors result in a non‐symmetric distribution of Asian and North American chum salmon in the open ocean. The directional swimming component contributes to the northward migration in summer. The model results indicate that during the first winter Asian chum salmon swim northward against the southward wind‐driven currents to stay in the western North Pacific. This suggests that Asian chum salmon require more energy to migrate than other stocks during the first winter of their ocean life. 相似文献
8.
CO2 concentration in a marine phytoplankton, Nannochloropsis sp., culture medium was observed to consider whether or not CO2 defficiency for growth occurs in the culture medium of a mass culture. In the first experiment, the Nannochloropsis sp. culture was continued for 4–5 days and the CO2 concentration was observed three times a day, namely, the initial, middle and end of the light period. While, in the second experiment, the CO2 concentration was observed every 2–3 hr for 24 hr on the second day after inoculation. In the first experiment, the total CO2 concentration decreased gradually throughout the culture period, repeating its decrease and increase in the light and dark periods, respectively. At the end of the light period of the third day after inoculation, the CO2 concentration decreased to concentrations which could not be determined. In the second experiment, the CO2 concentration decreased in the light period, and increased in the dark period. The increment in the dark period was faster at heavier aeration. It was considered that some kind of carbon source should be supplied to obtain high density of Nannochloropsis sp. ealier under strong light intensity. 相似文献
9.
The heritability of tolerance of wheat F3 lines to competition from annual ryegrass (Lolium rigidum), and its relationship to morphological traits, were determined using crosses between wheat cultivars with good and poor
competitive ability. Forty F2-derived F3 lines from a cross between two late flowering varieties (Machete × Spear) and 40 from a cross between early flowering varieties
(Wilgoyne × Gutha) were grown in the field with and without annual ryegrass. There was significant genetic variation between
lines within each of the two populations in a number of aspects of plant growth and development, including yield in monoculture.
The estimates of heritability for % yield loss due to competition were 0.25 and 0.57 in the two crosses respectively, indicating
that selection for high tolerance to competition in the F3 generation or later should be effective. Fairly strong relationships between height and % yield loss and between leaf length
and % yield loss suggest that these may be useful auxiliary traits when selecting for low % yield loss. However, differences
between crosses in the magnitude and sign of genetic and phenotypic correlation between traits indicate that competitive ability
is a complex character influenced by many factors.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
Summary Capsaicin contents were measured in the progenies from the test crosses between the strain, G5S17 derived from fruit with the graft-induced change in fruit shape and the original two cultivars, Yatsubusa (Capsicum annuum L. var fasciculatum
Ilish) and Spanish Paprika (C. annuum L. var. grossum
Sendt) used for grafting.The strain, G5S17 contained a lower amount of capsaicin than the original pungent cultivar Yatsubusa used as scion. The characteristic of the lowered capsaicin content in the strain has been stably inherited through seed propagation, and has also been transmitted to the progenies from the crosses with the original two cultivars used for scion or stock. These features in the capsaicin content agreed with those in fruit shape in the graft-induced change. 相似文献