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81.
The influence of indole-3-acetylaspartic acid (IAAsp) on rooting of stem cuttings from bean plants (Phaseolus vulgaris L.) of different ages, cultivated at different temperatures (17°, 21° and 25°C) was studied and compared to that of indole-3-acetic acid (IAA). At a concentration of 10–4 M, IAAsp only nonsignificantly stimulated adventitious root formation, approximately to the same level as IAA in all treatments. IAAsp at 5×10–4 M further enhanced rooting, by up 200% of control values, with little influence of temperature conditions and stock plant age. This concentration of IAA usually stimulated rooting more than the conjugate. The largest differences between the effects of IAAsp and IAA occured at the highest cultivation temperature of 25°C where stock plant age also influenced the response. The number of roots produced in comparison with the control, was enhanced from 350% on cuttings from the youngest plants to more than 600% on cuttings from the oldest. In contrast to the conjugate, 5×10–4 M IAA induced hypocotyl swelling and injury of the epidermis at the base of cuttings, in all treatments. 相似文献
82.
Merete Grung Frances M. L. D'Souza Michael Borowitzka Synnøve Liaaen-Jensen 《Journal of applied phycology》1992,4(2):165-171
Aplanospores ofHaematococcus pluvialis MUR 145 contained 0.7% carotenoids (dry wt. basis) consisting of β,β-carotene (5% of total carotenoid), echinenone (4%),
canthaxanthin (4%), (3S,3′S)-astaxanthin diester (34%), (3S,3′S)-astaxanthin monoester (46%), (3S,3′S)-astaxanthin (1%) and (3R,3′R,6′R)-lutein (6%).
The astaxanthin esters were examined by TLC and HPLC and VIS,1H NMR and mass spectra recorded. Their chirality was determined by the camphanate method (Vecchi & Müller, 1979) after anaerobic
hydrolysis.
The tough cell wall of the aplanospores required enzymatic treatment prior to pigment extraction. The potential use of this
microalga as a feed ingredient in aquaculture is discussed briefly. 相似文献
83.
Inhibited growth of common enteropathogenic bacteria in lactic-fermented cereal gruels 总被引:5,自引:0,他引:5
U. Svanberg E. Sjögren W. Lorri A. -M. Svennerholm B. Kaijser 《World journal of microbiology & biotechnology》1992,8(6):601-606
A natural lactic fermentation of mixtures of water and whole flour of either maize or high-tannin sorghum was obtained either before or after cooking to a weaning gruel: The preparations had a final pH of about 3.8 (range 3.67 to 4.00) and a ratio of lactic acid to acetic acid of 91 (w/w). The growth of added (about 107 c.f.u./g gruel) Gram-negative intestinal pathogenic bacteria, enterotoxigenicEscherichia coli, Campylobacter jejuni, Shigella flexneri andSalmonella typhimurium, was strongly inhibited in the sour gruels, and the effect could primarily be explained by the low pH caused by the formation of lactic and acetic acids during the fermentation process. Of the added Gram-positive bacteria,Bacillus cereus andStaphylococcus aureus showed similar inhibited growth up to 7h after inoculation in the sour gruels. The strain ofStaphylococcus, however, showed only a continued reduction in growth in the fermented gruel samples, which had a viable lactic bacteria culture indicating the presence of a bacteriocin. This implies that a low pH (< 4.0) alone is not sufficient to sustain the inhibition of the growth ofStaphylococcus aureus. The survival studies were carried out at optimal temperatures for each respective enteropathogen. 相似文献
84.
Zuzana Kossaczká Eva Machová Anna Vojtková-Lepšiková 《Applied microbiology and biotechnology》1991,36(3):375-378
Summary The yeast-like organism Aureobasidium pullulans efficiently converted abetd-xylose to cell mass (Y
X/S=0.45 g·g–1) with negligible production of polyols (Y
P/S=0.003 g·g–1) under aerobic conditions. A. pullulans grown semiaerobically exhibited different fermentation capacities in seven basal (vitaminless) medium and medium containing a mixture of seven vitamins. It was found that under semiaerobic conditions a mixture of vitamins significantly enhanced production of ethanol from abetd-xylose, resulting in a 15-fold higher yield coefficient of ethanol (Y
E/S=0.22 g·g–1) as compared to that achieved in vitaminless medium. This increase in ethanol production was accomplished at the expense of cell mass. A. pullulans produced extremely low amounts of polyols throughout all aerobic and semiaerobic experiments. A. pullulans displayed strictly NADPH-linked xylose reductase and NAD+-linked xylitol dehydrogenase activities. 相似文献
85.
Johan B. Steen Øivind Tøien Peder Fiske 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1991,161(2):155-158
1. | Physiological adaptation to hypothermia were studied in newly hatched great snipe chicks (Gallinago media) by measuring oxygen uptake (VO2), heart rate (HR), respiratory frequency (RF), and body temperature (Tb) at different ambient temperatures (Ta). |
2. | Tb of 1-day-old chicks at Ta of 35°C stabilized at about 40°C. At Ta between 20 and 30°C the chicks maintained a Tb about 8°C above Ta. Hatchlings maintained a higher gradient when active than when resting. Below 20°C they were unable to maintain a stable Tb. |
3. | In resting hatchlings VO2 was similar at Ta between 35 and 20°C (Tb 40–30°C), VO2 range 1.7–2.5 ml·g-1·h-1. Below 20°C, VO2 declined with time. |
4. | The HR of 1-day-old chicks fell linearly with Tb during cooling. The Q10 of the HR was 1.7 at Tb 38°C and increased to 3.0 at 29°C. The RF showed a slight tendency to decrease with decreasing Tb. |
5. | It is concluded that the ability to maintain normal dexterity at low Tb is an important aspect of snipe survival strategy. Maintaining a temperature gradient rather than a constant high Tb presumably saves energy. It is suggested that the mechanisms whereby VO2 is maintained at a low Tb may involve isoenzymes and adaptations of the nervous system. However, such adaptations would not seem to affect the pacemaker mechanism as evidenced by the high Q10 of the HR. |
86.
Per Sjögren 《Evolutionary ecology》1991,5(3):248-271
Summary Genetic variation in an isolated northern metapopulation of the pool frog (Rana lessonae) in Sweden was compared to that of Central European populations using enzyme electrophoresis and literature data. Of the 31 loci scored, two (EST-2 andIDH-2) were polymorphic while no variation occurred in seven of the eight loci which are polymorphic in Central European populations.The heterozygosity level of the Swedish pool frogs
is very low compared to that of other anuran populations, but their mean proportion of fertilized eggs within egg masses (97.5%) was not lower than in more heterozygous species, and their body size-specific fecundity did not differ from that of Polish conspecifics. The low genetic variability of the Swedish pool frogs is discussed in relation to features of the local populations such as size (N), calculated effective size (N
e
) reproductive success and probable history. It is concluded that long-term strong fluctuations in population size caused by reporductive failure in cold years have contributed more to the low genetic variability than could a single founder event due to a recent introduction by man. 相似文献
87.
P. Foxdal A. Sj?din B. ?stman B. Sj?din 《European journal of applied physiology and occupational physiology》1991,63(1):52-54
The aim of the study was to examine whether the difference in lactate concentration in different blood fractions is of practical importance when using blood lactate as a test variable of aerobic endurance capacity. Ten male firefighters performed submaximally graded exercise on a cycle ergometer for 20-25 min. Venous and capillary blood samples were taken every 5 min for determination of haematocrit and lactate concentrations in plasma, venous and capillary blood. At the same time, expired air was collected in Douglas bags for determination of the oxygen consumption. A lactate concentration of 4.0 mmol.l-1 was used as the reference value to compare the oxygen consumption and exercise intensity when different types of blood specimen and sampling sites were used for lactate analysis. At this concentration the exercise intensity was 17% lower (P less than 0.01) when plasma lactate was compared to venous blood lactate, and 12% lower (P less than 0.05) when capillary blood lactate was used. Similar discrepancies were seen in oxygen consumption. The results illustrated the importance of standardizing sampling and handling of blood specimens for lactate determination to enable direct comparisons to be made among results obtained in different studies. 相似文献
88.
Niels Gregersen Brage S. Andresen Peter Bross Vibeke Winter Niels Rüdiger Stefan Engst Ernst Christensen Daniel Kelly Arnold W. Strauss Steen Kølvraa Lars Bolund Sandro Ghisla 《Human genetics》1991,86(6):545-551
Summary A series of experiments has established the molecular defect in the medium-chain acyl-coenzyme A (CoA) dehydrogenase (MCAD) gene in a family with MCAD deficiency. Demonstration of intra-mitochondrial mature MCAD indistinguishable in size (42.5-kDa) from control MCAD, and of mRNA with the correct size of 2.4 kb, indicated a point-mutation in the coding region of the MCAD gene to be disease-causing. Consequently, cloning and DNA sequencing of polymerase chain reaction (PCR) amplified complementary DNA (cDNA) from messenger RNA of fibroblasts from the patient and family members were performed. All clones sequenced from the patient exhibited a single base substitution from adenine (A) to guanine (G) at position 985 in the MCAD cDNA as the only consistent base-variation compared with control cDNA. In contrast, the parents contained cDNA with the normal and the mutated sequence, revealing their obligate carrier status. Allelic homozygosity in the patient and heterozygosity for the mutation in the parents were established by a modified PCR reaction, introducing a cleavage site for the restriction endonuclease NcoI into amplified genomic DNA containing G985. The same assay consistently revealed A985 in genomic DNA from 26 control individuals. The A to G mutation was introduced into an E. coli expression vector producing mutant MCAD, which was demonstrated to be inactive, probably because of the inability to form active tetrameric MCAD. All the experiments are consistent with the contention that the G985 mutation, resulting in a lysine to glutamate shift at position 329 in the MCAD polypeptide chain, is the genetic cause of MCAD deficiency in this family. We found the same mutation in homozygous form in 11 out of 12 other patients with verified MCAD deficiency. 相似文献
89.
Summary A monoclonal mouse IgG2b antibody 19F8, directed towards a determinant on the retroviral transmembranous molecule p15E, binds selectively to certain rat tumours, including all tested yolk sac tumours, one rat colon carcinoma, one spontaneous kidney carcinoma and an adenovirus-type-9-induced rat breast tumour, as tested by antibody-dependent cellular cytotoxicity (ADCC) and immunohistochemistry. Groups of rats receiving yolk sac tumour F56 isografts intraperitoneally (i.p.) or subperitoneally (s.p.) were treated with this monoclonal antibody (mAb), 19F8, inoculated twice a week in doses of 100 µg. Parallel control groups received analogous inoculations of an isotype-matched monoclonal antibody. A significant growth inhibitory effect was observed with 19F8. In 5/10 rats isografted i.p., tumour outgrowth was completely inhibited and in the other 5 rats the outgrowth was delayed compared to the 10 rats in the control group, which all developed tumours. All rats of the control group developed large volumes of ascites, whereas the 5 rats in the therapy group with eventual tumour outgrowth had little or no ascites. In two experiments with rats carrying subperitoneal isografts and treated with the 19F8 mAb, tumour grew out in 4/5 and 5/10 rats, though growth was delayed compared to the control groups, in which 5/5 and 9/9 rats developed tumours. The tumours grew significantly more slowly in the therapy groups compared to the controls. All rats that developed tumours in the therapy groups showed an anti-idiotypic response against mAb 19F8. The single tumour-free rat in the first experiment and 1/5 tumour-free rats in the other showed no such response. The draining lymph node cells from the tumour-free animals showed a specific proliferative response to yolk sac tumour F56 cells in a mixed lymphocyte tumour cell culture (MLTC), and the MLTC-induced cells were cytotoxic to F56 but not to the natural-killer-sensitive rat T cell lymphoma G1—Tc1. The cytotoxic cell population was more than 90% CD4+. It is concluded that the two test systems for identification of the epitope of p15E detected by mAb 19F8 correlated well in detection of the epitope in the cells (immunohistochemistry) and at the cell surface (ADCC). It is also concluded that mAb 19F8 has a growth-inhibitory effect on yolk sac tumour F56 and that, as a result of the treatment, T cells with specificity for F56 are appearing in draining lymph nodes of tumour-free animals. 相似文献
90.
Levels of 7 alpha-hydroxy-4-cholesten-3-one in plasma reflect rates of bile acid synthesis in man 总被引:2,自引:0,他引:2
A method for analysis of 7 alpha-hydroxy-4-cholesten-3-one in plasma is described. Following solid-phase extraction/purification the compound is determined by high-performance liquid chromatography using a UV detector. The median concentration in healthy subjects was 12 ng/ml (range 3-40). The levels were lower in diseases associated with a low bile acid production: extrahepatic cholestasis, less than 1.5 ng/ml (range less than 0.9-3); liver cirrhosis less than 1.5 ng/ml (range less than 0.9-38), and higher in diseases associated with a high bile acid production: cholestyramine treatment, 188 ng/ml (range 54-477); ileal resection 397 ng/ml (range 128-750). The levels were essentially normal in patients with colon resection. The results are consistent with a strong positive correlation between the levels of 7 alpha-hydroxy-4-cholesten-3-one in plasma and the rate of bile acid synthesis. 相似文献