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771.
Dai Kusumoto Takashi Yonemichi Hiroki Inoue Tomonori Hirao Atsushi Watanabe Toshihiro Yamada 《Journal of Forest Research》2014,19(2):285-294
Pine wilt disease caused by the pine wood nematode (PWN), Bursaphelenchus xylophilus, has been epidemic and has had disastrous impacts on pine forests and forest ecosystems in eastern Asia. Many pine species in this area are susceptible to this disease. Pinus thunbergii is particularly susceptible. In Japan, tree breeders have selected surviving trees from severely damaged forests as resistant candidates, and have finally established several resistant varieties of P. thunbergii. However, this breeding procedure requires much time and effort due to the lack of physiological and phenotypical information about resistance. To investigate the resistance mechanisms of selected P. thunbergii, we compared histochemical responses, tissue damage expansion, and PWN distribution in resistant and susceptible clones of P. thunbergii after PWN inoculation. The results suggested that the mechanisms of resistance are as follows: damage expansion in the cortex, cambium, and xylem axial resin canals are retarded in resistant trees soon after inoculation, probably due to the induction of wall protein-based defenses. Suppression of PWN reproduction was particularly caused by inhibition of damage expansion in the cambium. The slow expansion of damage in each tissue provides time for the host to complete the biosynthesis of lignin in the walls of cells that surround the damaged regions. This lignification of cell walls is assumed to effectively inhibit the migration and reproduction of the PWNs. The mechanism of initial damage retardation is presumed to be a key for resistance. 相似文献
772.
Effects of water temperature on early development of Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis> 总被引:2,自引:0,他引:2
Akihiro Okamura Yoshiaki Yamada Noriyuki Horie Tomoko Utoh Naomi Mikawa Satoru Tanaka Katsumi Tsukamoto 《Fisheries Science》2007,73(6):1241-1248
ABSTRACT: To determine an optimal temperature range for efficient production of healthy eel larvae Anguilla japonica , the effect of water temperature on hatching, survival, and deformity rates was examined. The early ontogeny of morphological features in this species by incubating eggs at five different temperatures (19, 22, 25, 28 and 31°C) was examined. Hatching occurred at 24, 28, 46 and 58 h after fertilization when incubated at 28, 25, 22 and 19°C, respectively; no eggs hatched at 31°C. The growth rate of prefeeding larvae increased as water temperature was elevated and acquisition of feeding ability was also accelerated at higher temperature. Significantly high hatching rates (76–86%, P < 0.05) and survival rates (61–86%, P < 0.05) were observed at relatively high temperatures (22–28°C). The deformities were 'open lower jaw', 'pericardial edema', and 'notochordal bending', in which the mouth was deformed with a downward projecting lower jaw, the pericardial cavity was swollen, and the notochord was bent or twisted to various degrees, respectively. Open lower jaw and pericardial edema were especially predominant at 19°C, with rates of 68 and 92%, respectively, compared with 31 and 10% at 25 and 28°C, respectively. The occurrence of notochordal bending was not affected by temperature. The optimal temperature for incubation and rearing A. japonica eggs and prefeeding larvae is approximately 25–28°C. 相似文献
773.
Changes in serum thyroxine (T4), estradiol-17β (E2) and testosterone (T) levels during the parr-smolt transformation (smoltification) were investigated in the masu salmon (Oncorhynchus masou) in 1985 and 1987. T4 showed a peak in levels at the early stage of smoltification and E2 and T levels peaked almost at the same time. There were no significant differences between the concentrations of serum hormones
in female and males. During smoltification, germ cells in the peri-nucleolus and spermatogonia stage were present in the ovary
and testis, respectively. These results suggest that E2 and T may be involved in smoltification in the masu salmon. 相似文献
774.
Three-dimensional readout of flash x-ray images of living sperm in water by atomic-force microscopy 总被引:4,自引:0,他引:4
T Tomie H Shimizu T Majima M Yamada T Kanayama H Kondo M Yano M Ono 《Science (New York, N.Y.)》1991,252(5006):691-693
The imaging of living specimens in water by x-ray microscopy can be greatly enhanced with the use of an intense flash x-ray source and sophisticated technologies for reading x-ray images. A subnanosecond [corrected] x-ray pulse from a laser-produced plasma was used to record the x-ray image of living sea urchin sperm in an x-ray resist. The resist relief was visualized at high resolution by atomic-force microscopy. Internal structure of the sperm head was evident, and the carbon density in a flagellum was estimated from the relief height. 相似文献
775.
S. Matsumoto H. Yamada M. Iwata S. Adachi K. Yamauchi H. Ueda 《Fish physiology and biochemistry》2003,28(1-4):273-274
It was demonstrated that pregnenolone (P5) and 17α-hydroxypregnenolone (17α-OH-P5) were identified as cholesterol metabolites in the brain and pituitary gland of lacustrine sockeye salmon (Oncorhynchus nerka) during sexual maturation. Moreover, 17α-OH-P5 was determined as the major cholesterol metabolite. The conversion of P5 to 17α-OH-P5 in the brain and pituitary gland showed a clear regional difference, and their productivity were dramatically changed during sexual maturation. From these data, it was suggested that steroid converting enzyme in the brain and pituitary gland of lacustrine sockeye salmon might be involved in brain region-dependent roles on sexual maturation. 相似文献
776.
Fumiaki Takakuwa Ryota Tanabe Shohei Nomura Takashi Inui Shinichi Yamada Amal Biswas Hideki Tanaka 《Aquaculture Research》2022,53(1):36-49
Black soldier fly meal (BM) is an outstanding candidate as a fish meal (FM) substitute because it contains relatively high protein and essential amino acids. In this study, we replaced FM in red sea bream diets (Pagrus major) with BM to investigate its effect on growth and feed utilization. Six isonitrogenous and isolipidic experimental diets were prepared by substituting 0%, 20%, 40%, 60%, 80% and 100% FM protein with BM (Control, BM20, BM40, BM60, BM80 and BM100, respectively). After the 8-week feeding trial, final body weight, weight gain, specific growth rate and feed efficiency decreased linearly with increasing dietary BM level (p < 0.05). Apparent digestibility of protein and fat and serum total cholesterol concentration decreased with increasing dietary BM levels (p < 0.05) Final body weight, WG, SGR and FE against dietary BM level had breaking points of 76.2%, 41.7%, 76.5% and 60.0%, respectively, in segmental regression analysis. In conclusion, the results suggest that BM can replace a maximum of 41.7% of FM in the diet of red sea bream without compromising growth performance or feed efficiency for 56 days. 相似文献
777.
778.
Yamasaki M Mansho K Mishima H Kimura G Sasaki M Kasai M Tachibana H Yamada K 《Journal of agricultural and food chemistry》2000,48(12):6367-6371
The effect of dietary conjugated linoleic acid (CLA) on hepatic lipid parameters in Sprague-Dawley rats was examined. When rats were fed a diet containing CLA at 0 (control), 1, or 2% of the weight of the amount of food given for 3 weeks, the liver weight exhibited a slight increase in the CLA-fed groups, although the difference was not significant. Lipid accumulation in the hepatocytes of CLA-fed rats was also demonstrated by electron microscopic observation. In addition, the liver thiobarbituric acid reactive substances levels were significantly higher in the 2 wt % CLA group than in the other two dietary groups, and the levels of phosphatidylcholine hydroperoxide were higher in CLA-fed groups when compared to that of the control group. On the other hand, the serum lipid peroxide levels were comparable among all three dietary groups. Levels of triglycerides in the white adipose tissue (WAT) and serum nonesterified fatty acid (NEFA) were reduced in a CLA-dose-dependent manner. CLA was shown to accumulate in the WAT much more than in the serum or liver. These results suggest that CLA accelerates the decomposition of storage lipids in WAT and the clearance of serum NEFA levels, resulting in lipid peroxidation and a morphological change in the liver. 相似文献
779.
Barbara Fidalgo Paretsis Lara Carolina Mario Tais Harumi de Castro Sasahara Liege Cristina Garcia da Silva José Manoel dos Santos José Roberto Kfoury Júnior Rafael Magdanelo Leandro 《Anatomia, histologia, embryologia》2021,50(6):965-973
Kidney diseases are the most common illness for cats with a prevalence seven times higher than in dogs. Metanephros is the last of three renal systems to be formed during the embryonic period, which then becomes the permanent kidney. The current work aimed to analyse the morphology and to quantify the structures present in the development of metanephros from domestic cat (Felis catus) embryos and foetuses. For this purpose, the evaluation of the biometric parameters of metanephros from cat embryos and foetuses was performed in addition to the quantification of renal corpuscles and volume of cortical and medullary layers by stereological analysis. The evaluated biometric parameters were weight, width, height, thickness and volume. The values of the measured biometric parameters increased throughout the gestational stages. The quantity of renal corpuscles gradually increased following the embryo-foetal development, mainly during the middle of the gestational stage. It was during this phase that morphologically, a complete corticomedullary division was observed. Although the difference in the quantity of renal corpuscles between the middle and the end of the gestational stages was not statistically significant, there was an increase in the volume of the medullary layer and a decrease in the volume of the cortical layer between these two stages. These findings suggest that the metanephros presents a progressive growth with the renal corpuscles following this development until the middle of the gestational stage. Starting from this phase, the differentiation of the corticomedullary layers can be seen with a significant increase in the medullary layer. 相似文献
780.
The objective of this experiment was to investigate the effects of low-crude protein (CP) diets supplemented with rumen-protected lysine and methionine on growth performance, nitrogen excretion, and carcass traits in Holstein steers. Steers consumed the following diets: (1) 17.2% CP on a dry-matter basis during the early period (from 7 to 10 months of age) and 14.5% CP during the late period (from 10 to 18 months of age; CON, n = 4, initial body weight [BW] 238 kg), and (2) 14.4% CP during the early period and 11.4% CP during the late period (AA, n = 4, initial BW 243 kg). The AA diet contains rumen-protected lysine and methionine. Except for CP intake, feed intake and body weight gain were not affected by dietary CP content. Total nitrogen excretion per metabolic BW tended to be lower (p < .10) in the early period and significantly lower (p < .05) in the late period with decreasing the feed CP content. Plasma urea nitrogen concentrations were lower in AA than CON. Carcass traits and total free amino acid contents of the longissimus thoracis muscle were not affected by dietary CP content. Adding rumen-protected lysine and methionine to a low-CP diet would reduce nitrogen excretion in fattening Holstein steers without affecting productivity. 相似文献