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331.
Ramesh C. Thakur Susumu Goto Katsuaki Ishii S. Mohan Jain 《Journal of Forest Research》1999,4(2):157-160
Genetic stability of propagules regeneratedvia somatic embryogenesis is of paramount importance for its application to clonal forestry. Random amplified polymorphic DNA
(RAPD) markers were used to determine the genetic stability in somatic embryogenesis ofQuercus serrata Thunb. (Japanese white oak). Forty samples from an embryogenic line, consisting of regenerated plantlets, somatic embryos,
and embryogenic calli, were examined using 54 decanucleotide primers. A total of 6520 clear reproducible bands obtained from
these studies exhibited no aberration in RAPD banding pattern among the tested samples. Our results show that somaclonal variation
is absent in our plant propagation system. The genetic stability is discussed in terms of the origin of somatic embryos. 相似文献
332.
Shilta Madathampady Thomas Suresh Babu Padinhate Purayil Chadha Narinder Kumar Asokan Pillaru Kandiyil Vinod Kavungal Imelda Joseph Paramita Banerjee Sawant Ramya Abhijith 《Aquaculture Research》2019,50(10):2917-2931
The annual reproductive cycle of picnic seabream, Acanthopagrus berda (Forsskål, 1775), one of the potential aquaculture candidate from estuarine waters of Calicut, Kerala (India) was studied. Based on the morphological and histological studies, the ovotestes of A. berda were classified as active male, active female, inactive male, inactive female, transitional and undifferentiated. Histological observation of transitional gonads showed signs of degeneration in the testicular lobe, proliferation of connective tissue and empty sperm ducts indicating protandrous hermaphroditism in A. berda. Ovary was classified into seven maturity stages (virgin, developing virgin, developing, maturing, mature, running, spent) and testis into five maturity stages (resting, maturing, mature, running, spent). Gonadal development in A. berda indicated resting phase (February–July), pre‐spawning phase (March–August) and spawning phase (August–December). Inactive (24.6%) and active males (21.6%) were observed as dominant in smaller length classes (140–250 mm TL), whereas inactive (18%) and active females (51%) were observed as dominant in larger length classes (251–450 mm TL). Few primary females (28.1%) were observed in smaller (below 250 mm TL) and few primary males (28.5%) were observed in larger length classes (above 250 mm TL). From the present study, it can be concluded that in A. berda, most of the individuals function first as males and then change sex to female, but few continue to function as either male or female throughout their lifespan indicating digynous protandrous hermaphroditism. 相似文献
333.
Species of Schizochytrium are well known for their remarkable ability to produce lipids intracellularly. However, during their lipid accumulation, reactive oxygen species (ROS) are generated inevitably as byproducts, which if in excess results in lipid peroxidation. To alleviate such ROS-induced damage, seven different natural antioxidants (ascorbic acid, α-tocopherol, tea extract, melatonin, mannitol, sesamol, and butylated hydroxytoluene) were evaluated for their effects on the lipid accumulation in Schizochytrium sp. PKU#Mn4 using a fractional factorial design. Among the tested antioxidants, mannitol showed the best increment (44.98%) in total fatty acids concentration. However, the interaction effects of mannitol (1 g/L) and ascorbic acid (1 g/L) resulted in 2.26 ± 0.27 g/L and 1.45 ± 0.04 g/L of saturated and polyunsaturated fatty acids (SFA and PUFA), respectively, in batch fermentation. These concentrations were further increased to 7.68 ± 0.37 g/L (SFA) and 5.86 ± 0.03 g/L (PUFA) through fed-batch fermentation. Notably, the interaction effects yielded 103.7% and 49.6% increment in SFA and PUFA concentrations in batch fermentation. The possible mechanisms underlining those increments were an increased maximum growth rate of strain PKU#Mn4, alleviated ROS level, and the differential expression of lipid biosynthetic genes andupregulated catalase gene. This study provides an applicable strategy for improving the accumulation of SFA and PUFA in thraustochytrids by exogenous antioxidants and the underlying mechanisms. 相似文献
334.
Base‐line susceptibility for six‐day‐old larvae of the diamondback moth, Plutella xylostella, against Bacillus thuringiensis var kurstaki (Biobit®) was studied by a cabbage leaf disc dip bioassay technique. Diamondback moth from 13 locations in seven different states spread over a distance of about 3000 km longitudinally was used for these studies. Forty‐eight‐hour LC50 values varied from 1.0 to 10.97 mg AI litre−1. Further investigations on the development of resistance under laboratory conditions showed an increase in LC50 from 2.76 (for unselected F1 generation) to 5.28 mg AI litre−1 (for selected F9 generation), using a selection concentration of 6.4 mg AI litre−1. This suggested a possibility of the development of resistance under field conditions if there were to be extensive and indiscriminate use of B thuringiensis. These findings are discussed in relation to integrated pest management and the mechanisms of resistance in resistance management tactics. © 2000 Society of Chemical Industry 相似文献
335.
Thraustochytrids are well-known unicellular heterotrophic marine protists because of their promising ability to accumulate docosahexaenoic acid (DHA). However, the implications of their unique genomic and metabolic features on DHA production remain poorly understood. Here, the effects of chemical and physical culture conditions on the cell mass and DHA production were investigated for a unique thraustochytrid strain, PKU#SW8, isolated from the seawater of Pearl River Estuary. All the tested fermentation parameters showed a significant influence on the cell mass and concentration and yield of DHA. The addition of monosaccharides (fructose, mannose, glucose, or galactose) or glycerol to the culture medium yielded much higher cell mass and DHA concentrations than that of disaccharides and starch. Similarly, organic nitrogen sources (peptone, yeast extract, tryptone, and sodium glutamate) proved to be beneficial in achieving a higher cell mass and DHA concentration. PKU#SW8 was found to grow and accumulate a considerable amount of DHA over wide ranges of KH2PO4 (0.125–1.0 g/L), salinity (0–140% seawater), pH (3–9), temperature (16–36 °C), and agitation (140–230 rpm). With the optimal culture conditions (glycerol, 20 g/L; peptone, 2.5 g/L; 80% seawater; pH 4.0; 28 °C; and 200 rpm) determined based on the shake-flask experiments, the cell mass and concentration and yield of DHA were improved up to 7.5 ± 0.05 g/L, 2.14 ± 0.03 g/L, and 282.9 ± 3.0 mg/g, respectively, on a 5-L scale fermentation. This study provides valuable information about the fermentation conditions of the PKU#SW8 strain and its unique physiological features, which could be beneficial for strain development and large-scale DHA production. 相似文献
336.
随着抗生素在养殖行业使用加剧,施用粪肥导致的抗生素污染问题日趋严重,微生物降解抗生素作为解决这一问题的有效途径受到人们的广泛关注。本文综述了四环素类抗生素(TCs)的降解方法和微生物降解四环素类抗生素的研究现状,并对微生物降解四环素类抗生素的影响因素、降解路径以及其降解的分子机制进行了详细介绍。在此基础上,对微生物降解四环素类抗生素从实验室研究到实际生产应用进行了展望,指出了未来研究关注的重点。本文以期为人们深入认识四环素类抗生素的微生物修复提供参考,同时为四环素类抗生素的污染修复提供思路。 相似文献
337.