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91.
Atresia in the ovaries of sardine Sardina pilchardus did not show clear seasonal patterns. There was high prevalance ( c. 60%) and low intensity ( c. 1% of gonadal area occupied by oocytes) in all months of the spawning season studied. The batch size to ovary-free mass relationship was significantly different in the mid-spawning season, with higher relative fecundity and gonadosomatic index (IG ) in January than in November and March. There was no additional effect on batch fecundity due to age or condition factor. Data from monthly market samples during 1998–1999 revealed a continuous decline of the condition factor throughout the spawning season. The market samples also revealed that the duration of the spawning season is not equal for all fish. In any month, pre-spawning fish tended to have significantly higher IG than spawners, indicating that delayed initiation of spawning can lead to larger relative fecundity. The increase in sardine relative fecundity during the first half of the spawning season is probably due to the continuous influx of new spawners and possibly to body mass loss that is initially not translated into gonad mass loss. After January when all visible fat reserves within the body cavity have disappeared, the influx of new spawners practically ceases. 相似文献
92.
The numbers of first-batch eggs and workers (minims) in a carpenter ant Camponotus japonicus are not fixed but are regulated in response to various internal and external factors of founding queens. The initial body
weight of founding queens was positively correlated with the number of minims. The amount of queen weight loss during the
founding period was highly correlated with the number of minims. The numbers of first-batch eggs and minims for artificially
fed queens were significantly greater than those for control group queens and for unfed queens, respectively. The number of
eggs laid by a queen increased when eggs deposited in the early stage of founding were removed. In contrast, artificial addition
of alien eggs reduced the number of eggs laid by a queen. The adaptive implications of this flexibility in the production
of the first-batch brood in C. japonicus are discussed.
Received: December 18, 2000 / Accepted: March 19, 2001 相似文献
93.
面包酵母海藻糖积累条件的研究 总被引:3,自引:0,他引:3
对面包酵母的海藻糖积累条件及补料分批发酵进行了研究。结果表明 pH为 5 .0 ,温度 37℃有利于海藻糖积累。少量多次的补加葡萄糖可持续增加海藻糖的含量 ,但随着发酵时间的延长 ,葡萄糖对海藻糖转化率有逐渐减少的趋势。 相似文献
94.
Piccoli-Valle Roberta Hilsdorf Brandi Igor Viana Silva Daison Olzany Vieira Passos Frederico José 《World journal of microbiology & biotechnology》2001,17(5):433-437
Penicillium griseoroseum cultured in the presence of sucrose and yeast extract produces pectin lyase (EC 4.2.2.10) (PL) in the absence of its natural inducer pectin. This fungus was cultured in a fermenter at an aeration rate of 0.5 l/min for the first 25 h and 1.0 l/min for the remainder of the culture period, and at a stirring rate of 200 rev/min for the entire culture period. Fungal spores were inoculated directly into the fermenter at a final concentration of 5 × 104 spores/ml. The fungus was cultured in minimal medium supplemented with powdered dehydrated sugar cane juice, producing PL without added yeast extract. Maximum PL activity (0.067 IU/ml) was obtained after 65 h in batch culture. Pellet morphology of the mycelia made it possible to carry out three cycles of repeated batch culture. The same medium was used for renewal as for the single batch culture. The initial cycle was 53 h, after which approximately 0.103 IU/ml of PL was obtained. After this period, the medium was renewed and fermentation continued for two more cycles, which lasted approximately 20 h. Activity of PL obtained in the second cycle was approximately 0.118 IU/ml and in the third, approximately 0.109 IU/ml. 相似文献
95.
96.
Discriminating species of Sinipta Stål (Orthoptera: Acrididae) from Uruguay based on morphological,ethological and molecular data
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Eulalia Clemente Estrellita Lorier María‐Dolores GarcÍa Alejandro López‐lópez Juan‐José Presa 《Entomological Science》2018,21(2):225-240
Two species of the genus Sinipta, S. dalmani and S. hectorisperonii, exist in Uruguay, the latter reported here for the first time. Both species have quite similar morphological features and can only be distinguished by slight details, which have led to misidentifications in the past. Specimens from both taxa were studied in order to detect suitable characters to distinguish them and to clarify their taxonomic status, by integrating previously unstudied morphological, biological and molecular characteristics. Detailed structures of the stridulatory file of both sexes were studied and described for the first time, and the sounds produced by both species were studied and described on the basis of recordings made in captivity with an analog recorder. The signal was digitized and analyzed using Avisoft software. Three different types of sound were described for both species: calling song, courtship song and disturbance song. Oscillograms and frequency spectra were provided, and the physical characteristics of the sounds of interest for species identification were established. Finally, molecular studies showed that the two taxa are reciprocally monophyletic groups. The combined results of the analyses suggest that the two studied taxa are distinct species, and point to features suitable for their identification. 相似文献
97.
Effects of temperature shift on cell cycle, apoptosis and nucleotide pools in CHO cell batch cultues
Moore A Mercer J Dutina G Donahue CJ Bauer KD Mather JP Etcheverry T Ryll T 《Cytotechnology》1997,23(1-3):47-54
Temperature reduction in CHO cell batch culture may be beneficial in the production of recombinant protein and in maintenance of viability. The effects on cell cycle, apoptosis and nucleotide pools were studied in cultures initiated at 37°C and temperature shifted to 30 °C after 48 hours. In control cultures maintained at 37 °C, viable cells continued to proliferate until the termination of the culture, however, temperature reduction caused a rapid decrease in the percent of cells in S phase and accumulation of cells in G-1. This was accompanied by a concurrent reduction in U ratio (UTO/UDP-GNAc), previously shown to be a sensitive indicator of growth rate. Culture viability was extended following temperature shift, as a result of delayed onset of apoptosis, however, once initiated, the rate and manner of cell death was similar to that observed at 37 °C. All nucleotide pools were similarly degraded at the time of apoptotic cell death. Temperature reduction to 30 °C did not decrease the energy charge of the cells, however, the overall rate of metabolism was reduced. The latter may be sufficient to extend culture viability via a reduction in toxic metabolites and/or limitation of nutrient deprivation. However, the possibility remains that the benefits of temperature reduction in terms of both viability and productivity are more directly associated with cultures spending extended time in G-1. 相似文献
98.
Cultivation of Acinetobacter radioresistens on n-hexadecane for lipase production was investigated with repeated batch culture in the presence of a hydrophobic nonwoven fabric. Lipase production followed the growth-associated model, and the repeated batch culture could achieve both high enzyme yield and increased volumetric productivity. The fabric was shown to be able to disperse n-hexadecane, to adsorb the unused hydrocarbon, and to retain bioemulsifiers excreted from the cells; therefore, it enhanced cell growth and, in turn, lipase production. In the repeated batch culture in the absence of the fabric, lipase yield and volumetric productivity were found to be 21 U/mL and 875 U/L. h, respectively. However, if the fabric was equipped in the fermentor, lipase yield and volumetric productivity increased to 30 U/mL and 2500 U/L. h, respectively. The lipase production profile could be further improved by raising the amount of nitrogen source and, as a result, a lipase yield of 54 U/mL and a volumetric productivity of 2250 U/L. h were obtained. In this study we assess the beneficial effects of nonwoven fabric on lipase production. 相似文献
99.
Different fermentation strategies by Schizochytrium mangrovei strain pq6 to produce feedstock for exploitation of squalene and omega‐3 fatty acids
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Thom Thi Le Thi Huong Quynh Hoang Van Nhat Pham Minh Hien Thi Hoang Hoai Thu Thi Ngo Dang Diem Hong 《Journal of phycology》2018,54(4):550-556
Schizochytrium mangrovei strain PQ 6 was investigated for coproduction of docosahexaenoic acid (C22: 6ω‐3, DHA ) and squalene using a 30‐L bioreactor with a working volume of 15 L under various batch and fed‐batch fermentation process regimes. The fed‐batch process was a more efficient cultivation strategy for achieving higher biomass production rich in DHA and squalene. The final biomass, total lipid, unsaponifiable lipid content, and DHA productivity were 105.25 g · L?1, 43.40% of dry cell weight, 8.58% total lipid, and 61.66 mg · g?1 · L?1, respectively, after a 96 h fed‐batch fermentation. The squalene content was highest at 48 h after feeding glucose (98.07 mg · g?1 of lipid). Differences in lipid accumulation during fermentation were correlated with changes in ultrastructure using transmission electron microscopy and Nile Red staining of cells. The results may be of relevance to industrial‐scale coproduction of DHA and squalene in heterotrophic marine microalgae such as Schizochytrium . 相似文献
100.
Phototrophic cultivation of NaCl‐tolerant mutant of Spirulina platensis for enhanced C‐phycocyanin production under optimized culture conditions and its dynamic modeling
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Apurva Gupta Devendra Mohan Rishi Kumar Saxena Surendra Singh 《Journal of phycology》2018,54(1):44-55
Commercial cultivation of Spirulina sp. is highly popular due to the presence of high amount of C‐phycocyanin (C‐PC ) and other valuable chemicals like carotenoids and γ‐linolenic acid. In this study, the pH and the concentrations of nitrogen and carbon source were manipulated to achieve improved cell growth and C‐PC production in NaCl‐tolerant mutant of Spirulina platensis . In this study, highest C‐PC (147 mg · L?1) and biomass (2.83 g · L?1) production was achieved when a NaCl‐tolerant mutant of S. platensis was cultivated in a nitrate and bicarbonate sufficient medium (40 and 60 mM, respectively) at pH 9.0 under phototrophic conditions. Kinetic study of wildtype S. platensis and its NaCl‐tolerant mutant was also done to determine optimum nitrate concentrations for maximum growth and C‐PC production. Kinetic parameter of inhibition (Haldane model) was fitted to the relationship between specific growth rate and substrate concentration obtained from the growth curves. Results showed that the maximum specific growth rate (μmax) for NaCl‐tolerant mutant increased by 17.94% as compared to its wildtype counterpart, with a slight increase in half‐saturation constant (Ks), indicating that this strain could grow well at high concentration of NaNO3. C‐PC production rate (Cmax) in mutant cells increased by 12.2% at almost half the value of Ks as compared to its wildtype counterpart. Moreover, the inhibition constant (Ki) value was 207.85% higher in NaCl‐tolerant mutant as compared to its wildtype strain, suggesting its ability to produce C‐PC even at high concentrations of NaNO3. 相似文献