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51.
Thawatchai Ngamsiri Masamichi Nakajima Srijanya Sukmanomon Naruepon Sukumasavin Wongphatom Kamonrat Uthairat Na-Nakorn Nobuhiko Taniguchi 《Fisheries Science》2007,73(4):792-799
The Mekong giant catfish Pangasianodon gigas is endemic to the Mekong River and is a critically endangered species. The genotypes of the microsatellite DNA (msDNA) and
mitochondrial DNA (mtDNA) markers (right domain of the control region) were detected to evaluate the present status of genetic
divergence of this species from the Mekong River in Thailand and Cambodia. The observed and expected heterozygosity values
of Mekong giant catfish in Thailand and Cambodia were relatively low in comparison with those of other nonendangered freshwater
fish species. These two populations from Thailand and Cambodia showed similar levels of genetic diversity, as evaluated by
the 384 nucleotides of the mtDNA control region with 13 haplotypes. The pairwise F
ST value between the two populations based on the genotype frequencies of msDNA and mtDNA markers suggested a close genetic
relationship between the populations in Thailand and Cambodia. The results of this study support the conclusion that the Mekong
giant catfish is critically endangered. Care should be taken to sustain the genetic diversity of this species, as the level
of genetic variability has already decreased in the wild population. This species is a target species for an ongoing stock
enhancement program in the Mekong River in Thailand. It is proposed to apply these markers for proper broodstock management,
such as for minimal kinship selective breeding in the hatchery. 相似文献
52.
Ishihara K Warita K Tanida T Sugawara T Kitagawa H Hoshi N 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2007,69(4):347-352
In 1976, men who were exposed to the highest concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) after an explosion at a chemical plant near Seveso, Italy, produced more girls than boys. However, few studies have examined the possibility that the exposure of laboratory animals to TCDD, especially that of males, could lead to a lower male/female sex ratio. The aim of this study was to investigate whether direct paternal exposure to TCDD affects the sex ratio of offspring using a relatively large-scale experimental design. Male ICR mice (n=120) were randomly assigned to three, one of which served as a vehicle control, the other two were administered TCDD orally with an initial loading dose of 2 or 2,000 ng TCDD/kg, followed by a weekly maintenance dose of 0.4 (T2/0.4 group) or 400 (T2000/400 group) ng/kg prior to mating. The major organs of each mouse were weighed and histopathologically and immunohistologically investigated, and the sex ratio of offspring [males/(males + females) x 100] was calculated in each dam. There were no significant effects on organ weights, or on the structure of the testis and epididymis between the control and TCDD-exposed males, but TCDD administration produced a significantly lower proportion of male offspring from T2000/400-exposed sires despite no alteration in litter size (Control: 53.1 +/- 1.7; T2/0.4: 48.8 +/- 2.5; T2000/400: 46.2 +/- 2.1). In addition, we further divided the T2000/400 group into 3 subgroups based on the proportion of CYP1A1-immunoreactive areas in the liver; there was a significant correlation between sex ratio and CYP1A1 immunoreactivity. Thus, the present study confirms that direct paternal exposure to TCDD might be associated with an alteration in the sex ratio of offspring. Possible mechanisms through which TCDD might decrease the fertility potential of Y-bearing gametes before conception are discussed. 相似文献
53.
Yoshihiro KOBAYASHI Tetsushi HIRANO Takuya OMOTEHARA Rie HASHIMOTO Yuria UMEMURA Hideto YUASA Natsumi MASUDA Naoto KUBOTA Kiichi MINAMI Shogo YANAI Mitsuko ISHIHARA-SUGANO Youhei MANTANI Toshifumi YOKOYAMA Hiroshi KITAGAWA Nobuhiko HOSHI 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(11):1355-1361
54.
Tomoya Matsuyama Yasunori Nakajima Kazuo Matsuya Makoto Ikenaga Susumu Asakawa Makoto Kimura 《Soil biology & biochemistry》2007,39(2):463-472
Plant residues (PRs) are “hot spots” of microbial activities in soil. PRs with the size more than 0.5 mm were collected from a Japanese paddy field during rice cultivation period (from May to September) and fractionated into four categories by size (>4, 2-4, 1-2, and 0.5-1 mm) using sieves. Restriction fragment length polymorphism (RFLP) and denaturing gradient gel electrophoresis (DGGE) patterns were compared among the fractions after DNA extraction from the PRs and PCR amplification. The total amount of PRs with the size over 0.5 mm decreased in the field with the first-order kinetics (r2=0.810, p<0.01) with time from rice transplanting to harvest. RFLP analysis showed that the bacterial community structure in PRs with the 0.5-2 mm fraction was different from that in PRs with the >2 mm fraction and the latter community structure changed after the midseason drainage. In contrast, the DGGE patterns of the bacterial community in the PRs indicated the succession from June to September during rice cultivation forming three major groups irrespective of the fraction size. Sequence analysis of DGGE bands showed that Firmicutes (clostridia), α-, γ-, δ-Proteobacteria (myxobacteria), Nitrospira, Acidobacteria, Bacteroidetes, Verrucomicrobia and Spirochaetes were predominant members in the PRs irrespective of fraction size. 相似文献
55.
人工合成甘蓝型油菜的繁育特性与试管繁殖 总被引:5,自引:0,他引:5
通过甘蓝品种(2n=18,CC)与白菜品种(2n=20,AA)杂交并借助胚珠培养和染色体加倍,获得一系列人工甘蓝型油菜新品系。对18个人工合成甘蓝型油菜新品系的花粉育性、自交结实性、异交结实性等研究表明,人工油菜品系花期自交不结实或结实率很低。蕾期自交一朵花平均获3.6粒种子,平均结角率为19.7%。但是,人工甘蓝型油菜无论作父本还是作母本与天然甘蓝型油菜杂交的结实率都较高。以人工油菜作父本与天然油菜杂交。42个组合平均杂交一朵花获得10.3粒杂交种子;以人工油菜作母本与天然油菜杂交,15个组合平均杂交一朵花获得8.5粒杂交种子。分析结果表明。本试验的人工油菜品系具有很强的自交不亲和性,蕾期自交结实率也较低,但对异交结实影响不大,因此可以直接用于杂种生产。试验对自交结实特别困难的5个人工甘蓝型油菜新品系进行了试管繁殖,采取子叶、下胚轴和茎尖联合培养方式。22株无菌苗经过2个月快繁,获得260株苗。平均繁殖系数为12.4。不同基因型繁殖系数差异较大。变幅为3.3~21.0。 相似文献
56.
Ryo D. Obara Yuki Kato Yoshiji Asaoka Miho Mukai Keigo Matsuyama Kae Fujisawa Minako Tajiri Tamio Fukushima Mikinori Torii 《Journal of toxicologic pathology》2021,34(3):261
A 6-month-old female beagle dog, assigned to the low-dose group in a toxicity study, was evaluated for compound toxicity, and spontaneous hyperadrenocorticism was suspected. The animal had an externally apparent distended abdomen on clinical examination upon arrival. Pre-dose clinical pathology showed slightly higher erythroid parameters and stress leukogram on hematology; plasma biochemistry showed higher total protein, gamma-glutamyl transferase, total cholesterol, and triglyceride levels than the reference data. On necropsy, a prominent increase in adipose tissues of the subcutis and abdomen and increased weight of the adrenal gland and liver were observed. Histopathology revealed diffuse hyperplasia of adrenocortical cells in the zona fasciculata and reticularis, cortical atrophy of the thymus, and abundant glycogen accumulation in the hepatocytes. These findings were incidental and not test-substance-related. Electron microscopy of the adrenocortical cells in the zona fasciculata revealed decreased typical translucent lipid droplets, increased electron-dense lipid droplets, and abundant smooth endoplasmic reticulum and lysosomes. Additionally, increased numbers of various sizes and forms of mitochondria with tubular, vesicular, or lamellar cristae compared to that of normal animals were observed. These ultrastructural characteristics of the adrenocortical cells suggested hyperfunction. The pre-dose plasma cortisol levels were slightly higher than those of other females assigned to the toxicity study, while plasma adrenocorticotropic hormone levels were within the normal range. These findings indicate that hyperadrenocorticism is a possible cause of the systemic changes in this case. 相似文献
57.
58.
Makoto Shirai Shingo Arakawa Hiroaki Miida Takuya Matsuyama Junzo Kinoshita Toshihiko Makino Kiyonori Kai Munehiro Teranishi 《Journal of toxicologic pathology》2013,26(2):175-186
To assess modification of thioacetamide-induced hepatotoxicity in mice fed a high-fat
diet, male C57BL/6J mice were fed a normal rodent diet or a high-fat diet for 8 weeks and
then treated once intraperitoneally with thioacetamide at 50 mg/kg body weight. At 24 and
48 hours after administration, massive centrilobular hepatocellular necrosis was observed
in mice fed the normal rodent diet, while the necrosis was less severe in mice fed the
high-fat diet. In contrast, severe swelling of hepatocytes was observed in mice fed the
high-fat diet. In addition, mice fed the high-fat diet displayed more than a 4-fold higher
number of BrdU-positive hepatocytes compared with mice fed the normal rodent diet at 48
hours after thioacetamide treatment. To clarify the mechanisms by which the hepatic
necrosis was attenuated, we investigated exposure to thioacetamide and one of its
metabolites, the expression of CYP2E1, which converts thioacetamide to reactive
metabolites, and the content of glutathione S-transferases in the liver. However, the
reduced hepatocellular necrosis noted in mice fed the high-fat diet could not be explained
by the differences in exposure to thioacetamide or thioacetamide sulfoxide or by
differences in the expression of drug-metabolizing enzymes. On the other hand, at 8 hours
after thioacetamide administration, hepatic total glutathione in mice fed the high-fat
diet was significantly lower than that in mice fed the normal diet. Hence, decreased
hepatic glutathione amount is a candidate for the mechanism of the attenuated necrosis. In
conclusion, this study revealed that thioacetamide-induced hepatic necrosis was attenuated
in mice fed the high-fat diet. 相似文献
59.
60.
Takashi Kuriwada Norikuni Kumano Keiko Shiromoto Dai Haraguchi Takashi Matsuyama Tsuguo Kohama 《国际虫害防治杂志》2014,60(3):160-165
Sterile insect technique (SIT) is widely used to eradicate target pest species. Its effectiveness depends on the ability of released sterile males to mate with wild females. In pest species with a female choice mating system, there is potential for female preference to evolve in the wild population in view of the resulting zero-fitness in females that mate with sterile males. The evolution of female preference against sterile males can, therefore, reduce the efficiency of the SIT as the likelihood decreases that sterile males will mate with wild females. We examined this experimentally by using the solanaceous fruit fly Bactrocera latifrons, a serious pest of solanaceous crops, by allowing female preference in mass-reared fruit flies to select between fertile and sterile males over 12 generations. However, this did not generate a rapid evolutionary response. Also the remating rate of females did not increase, even when the first mating partner was a sterile male. We discuss the implication of the results for the eradication project by the SIT program. 相似文献