The allometric relationships for plant daily biomass production rates, different measures of body size (dry weight and length)
and photosynthetic biomass per plant are reported for two mutants of Arabidopsis thaliana (abi1-1, insensitive to ABA; era1-2, hypersensitive to ABA). Scaling relationships, such as daily rate of growth (G) vs body mass (M), plant body length or plant height (L) vs body mass (M), photosynthetic biomass (Mp) vs non-photosynthetic biomass (Mn), and daily rate of growth (G) vs. photosynthetic biomass (Mp) were significantly different in abi1-1 and era1-2. It is implied that the sensitivity to abscisic acid may change the scaling relationships for plant biomass production rate
and body size in Arabidopsis thaliana. Because these scaling relationships are closely related to sensitivity to abscisic acid, they are of importance for phytohormonal
ecology. 相似文献
The amino acid and humic acid requirements of Saccharothrix algeriensis NRRL B-24137 for growth and production of the dithiolopyrrolone antibiotics were studied in a semi-synthetic medium (SSM). Nature and concentration of amino acids and humic acid strongly influenced the growth and dithiolopyrrolone specific production.
The highest value of thiolutin (acetyl-pyrrothine) specific production was obtained in the presence of 1 g/l humic acid (336 mg/g DCW), and in the presence of 5 mM l-cystine (309 mg/g DCW) as compared to 19 mg/g DCW obtained with the control. Furthermore, thiolutin production was increased about six-fold, four-fold and three-fold in the presence of l-proline, l-glutamic acid and dl-histidine, respectively. In contrast, the production of thiolutin was reduced by addition of other amino acids such as l-glutamine, dl-ethionine, l-methionine and l-arginine. The highest value of isobutyryl-pyrrothine production was obtained in the presence of 2,6-diaminopimelic acid and l-lysine (7.8 and 1.0 mg/g DCW, respectively). However, the highest value of butanoyl-pyrrothine production was obtained in the presence of humic acid (6.6 mg/g DCW), followed by l-cysteine and l-proline (3.6 and 3.2 mg/g DCW, respectively). In addition, the maximum specific production of senecioyl-pyrrothine (29 mg/g DCW) and tigloyl-pyrrothine (21 mg/g DCW) was obtained in the presence of humic acid. We found that, except for isobutyryl-pyrrothine, production of all dithiolopyrrolones was favoured by addition of l-proline. The maximum specific production was obtained with l-proline at concentrations of 2.50 mM for thiolutin (133 mg/g DCW), 1.25 mM for senecioyl-pyrrothine, tigloyl-pyrrothine and butanoyl-pyrrothine production (29, 23 and 3.9 mg/g DCW, respectively). Production of all dithiolopyrrolones strongly decreased as the l-methionine or dl-ethionine concentration was increased in the culture medium. 相似文献
By systematic investigation, glutamate and a mixture of metal ions were identified as factors limiting the production of nattokinase in Bacillus subtilis. Consequently, in medium supplemented with these materials, the recombinant strain secreted 4 times more nattokinase (260 mg l−1) than when grown in the unsupplemented medium. 相似文献
The effects of oxygen supply within the range 20.8–50% (using pure oxygen and air), on cell cultures of Panax ginseng were investigated in a balloon-type bubble bioreactor (5 L capacity, containing 4 L Murashige and Skoog medium, supplemented with 7.0 mg L−1 indolebutyric acid, 0.5 mg L−1 kinetin and 30 g L−1 sucrose). A 40% oxygen supply was found to be optimal for the production of both cell mass and saponin yielding values of 12.8 g (DW) L−1, 4.5 mg (g DW)−1 on day 25, respectively. Low (20.8%, 30%) and high (50%) oxygen concentration supplies were unfavorable to cell growth and saponin accumulation. The results indicate that oxygen supplementation to bioreactor-based ginseng cultures was beneficial for biomass accumulation and saponin production. 相似文献
Life-history and production of Olinga feredayi in both benthic and hyporheic stream habitats were investigated in a pristine Waikato, New Zealand, forest stream over two
years to investigate the contribution of hyporheic habitat to total secondary production. O. feredayi had a univoltine life-history with adult emergence occurring from November to March. Larvae with case lengths < 2 mm were
present on most dates suggesting delayed egg hatching. Benthic densities were inversely related to maximum peak daily flow
in the month prior to sampling, and positively related to the dry mass of particulate organic matter present in samples. Reach-average
benthic production calculated by the size-frequency method was 0.024 g DM m−2 year−1. Hyporheic production was 4.276 g DM m−3 year−1 and 6.462 g DM m−3 year−1 in colonisation baskets set at 15–30 cm and 30–45 cm within the substratum, respectively, 2.3–3.4 times greater than production
in surface baskets (0–15 cm). Averaged out over the reach scale, it was estimated that 96% of annual secondary production
of O. feredayi occurred in hyporheic habitats >10 cm below the streambed surface. Our study clearly demonstrates that only sampling benthic
habitats can lead to gross under-estimation of population-level annual production, and provides evidence for the role of the
hyporheos as a source of secondary production that may partly account for the Allen Paradox. 相似文献
Ability to store resources that will be used for reproduction represents a potential life history adaptation because storage
permits feeding and reproduction to be decoupled spatially and/or temporally. The two ends of a continuum involve acquiring
all resources prior to reproduction (capital breeding) or acquiring all resources during the reproductive period (income breeding).
Traditional life history theory examines tradeoffs between costs and benefits of such strategies, but this theory has not
been integrated into life history studies of ants, even though founding queens have the analogous strategies of fully claustral
(capital breeding) and semi-claustral (income breeding). This study demonstrates that facultatively semi-claustral queens
of the seed-harvester ant Pogonomyrmex desertorum exhibit phenotypic plasticity during colony founding because unfed queens produced few, small minims, whereas ad libitum
fed queens produced larger, heavier minims and additional brood. Fed queens also lost less mass than unfed queens despite
their producing more brood. Overall, foraging provides queens with a suite of benefits that likely offset potential negative
effects of foraging risk.
Life history studies across a diverse array of taxa show that capital breeding is consistently associated with low availability
and/or unpredictability of food, i.e., environmental conditions that favor prepackaging of reproductive resources. Such a
broad and consistent pattern suggests that similar factors favored the evolution of fully claustral (capital breeding) colony
founding in ants. Overall, these data suggest that ant researchers should revise their conventional view that fully claustral
colony founding evolved because it eliminated the need for queens to leave the nest to forage. Instead, colony founding strategies
should be examined from the perspective of environmental variation, i.e., availability and predictability of food. I also
provide a functional scenario that could explain the evolution of colony founding strategies in ants.
Received 16 November 2005; revised 1 March 2006; accepted 29 March 2006. 相似文献
Caste fate conflict is expected in Melipona bees because queens and workers are the same size and are reared in identical sealed cells. Extrinsic and intrinsic colonial
factors, however, seem to have limiting effects on queen production. The consequences of colonial conditions on both queen
and worker production, particularly the effects of food storage in the colonies, are still poorly understood. Here, we investigated
whether caste production in seven natural colonies of Melipona compressipes fasciculata was affected by food resources, seasonal factors, or internal factors. The results showed that, at the populational level,
about 5% of the females developed into gynes; in the strongest colony, 12.7% of the females developed into gynes. Male production
was verified only in stronger colonies. We suggest that caste ratio is primarily affected by intra-colonial conditions rather
than by food resources.
Received 1 November 2005; revised 30 January 2006; accepted 17 February 2006. 相似文献
Several methods have been described to enhance antibody-dependent cellular cytotoxicity (ADCC) using different host cells that produce antibody with reduced levels of fucose on their carbohydrates. We compared the suitability of these methods for the serum-free fed-batch production of antibody for clinical trials and commercial uses. Recombinant anti-human CD20 chimeric IgG1-producing clones were established from host-cells that have been shown to produce more than 90% fucose-negative antibody. The cell lines were a FUT8 (alpha-1,6-fucosyltransferase) knockout Chinese hamster ovary (CHO) cell line, Ms704, and two Lens culinaris agglutinin (LCA)-resistant cell lines, one derived from a variant CHO line, Lec13 and the other from a rat hybridoma cell line, YB2/0. The amount of fucose-negative antibody produced by Lec13 and YB2/0 significantly decreased with the culture. The increase in fucosylation was due to remaining synthesis of GDP-fucose via de novo pathway for the CHO line and the elevation of FUT8 expression by the YB2/0 cells. In contrast, Ms704 cells stably produced fucose-negative antibody with a consistent carbohydrate structure until the end of the culture. The productivity of the Ms704 cells reached 1.76 g/L with a specific production rate (SPR) of 29 pg/cell/day for 17 days in serum-free fed-batch culture using a 1 L spinner bioreactor. Our results demonstrate that FUT8 knockout has the essential characteristics of host cells for robust manufacture of fucose-negative therapeutic antibodies with enhanced ADCC. 相似文献
The use of Moloney murine leukaemia virus (MoMLV) derived retroviral vectors in gene therapy requires the production of high titer preparations. However, obtaining high titers of infective MoMLV retroviral vectors is difficult due to the vector inherent instability. In this work the effect of the cell culture medium osmotic pressure upon the virus stability was studied. The osmolality of standard medium was raised from 335 up to 500 mOsm/kg using either ionic (sodium chloride) or non-ionic osmotic agents (sorbitol and fructose). It was observed that, independently of the osmotic agent used, the infectious vector inactivation rate was inversely correlated with the osmolality used in the production media; therefore, the use of high medium osmolalities enhanced vector stability. For production purposes a balance must be struck between cell yield, cell productivity and retroviral stability. From the conditions tested herein sorbitol addition, ensuring osmolalities between 410 and 450 mOsm/kg, yields the best production conditions; NaCl hampered the viral infectious production while fructose originates lower cell yields. Lipid extractions were performed for cholesterol and phospholipid analyses showing that more stable viral vectors had a 10% reduction in the cholesterol content. A similar reduction in cholesterol was observed in the producer cells. A detailed analysis of the major phospholipids composition, type and fatty acid content, by mass spectrometry did not show significant changes, confirming the decrease in the cholesterol to phospholipids ratio in the viral membrane as the major reason for the increased vector stability. 相似文献